JP2020122816A - Ferrule and optical connector - Google Patents

Abstract

To provide a ferrule and an optical connector allowing easy mounting of a lens-attached optical fiber including a GRIN lens fused and connected to the tip of an optical fiber while suppressing increase in optical connection loss.SOLUTION: The ferrule comprises a main body part 11 for holding a plurality of lens-attached optical fibers 5 including a GRIN lens 7 fused and connected to the tip of an optical fiber. The main body part includes a lower member 13 having a plurality of grooves 13b extending along an X direction and arrayed along a Y direction, and an upper member 14 facing the plurality of grooves and other than the lower member. The groove includes a first region supporting the optical fiber, and a second region R2 positioned between the first region and a front end face and supporting the GRIN lens. The lower member further includes a first recess 13f provided between the first region and the second region. The first recess stores a fusion part F between the optical fiber and the GRIN lens.SELECTED DRAWING: Figure 4

Description

The present invention relates to a ferrule and an optical connector.

Patent Document 1 discloses a non-contact type optical connector. This optical connector includes a plurality of optical fibers and a ferrule having a plurality of holding holes that respectively hold the plurality of optical fibers. This optical connector optically connects the optical fibers with each other while facing the other optical connector with a gap. A GRIN lens is arranged at the tip of the optical fiber, and the GRIN lens is arranged at the tip of the ferrule.

Japanese Unexamined Patent Publication No. 2016-061942

The ferrule used for the multi-core optical connector is molded, for example, by injecting a resin into a mold having a core pin for forming a plurality of holding holes and solidifying the resin. In this case, in the step of solidifying the resin, the core pin of the mold may be bent due to the contraction of the resin, and accordingly, the holding hole of the ferrule may also be bent. When such bending occurs, the GRIN lens held in the holding hole tends to tilt. If the attitude of the GRIN lens near the tip surface of the optical connector is tilted, the GRIN lens may be misaligned on the tip surface, which may increase the optical connection loss between the optical connectors.

Further, as a method of connecting the GRIN lens and the optical fiber, a method of fusion-bonding the GRIN lens to the tip of the optical fiber can be considered. In this case, the fusion-bonded portion where the optical fiber and the GRIN lens are fused is apt to be thicker than the other portions. If the fused portion is thicker than the holding hole of the ferrule, it may be difficult to insert the fused portion into the holding hole. Since the length of the GRIN lens is limited to a certain length in order to suppress an increase in optical connection loss, when the fusion thickening occurs, the fusion bonded portion interferes with the GRIN lens holding hole. It may not be possible to insert it all the way to the tip. On the other hand, it is possible to make the holding hole thicker than the fusion-bonded portion, but in this case, the clearance between the holding hole and the GRIN lens becomes large. As a result, misalignment of the GRIN lens is likely to occur and optical connection loss may increase.

The present invention has been made in view of the above problems, and it is possible to easily mount a lensed optical fiber in which a GRIN lens is fusion-spliced to a tip of an optical fiber while suppressing an increase in optical connection loss, and a ferrule and an optical fiber. It is intended to provide a connector.

A ferrule according to an embodiment of the present invention includes a main body that holds a plurality of lensed optical fibers in which a GRIN lens is fusion-spliced to a tip of the optical fiber, and the main body has a first end that intersects with a front end face of the optical fiber. A first member including a plurality of grooves extending along the direction and aligned along a second direction intersecting the first direction; and a second member facing the plurality of grooves and separate from the first member. And the groove includes a first region that supports the optical fiber and a second region that is located between the first region and the front end face and that supports the GRIN lens, and the first member is The first recess further includes a first recess provided between the first region and the second region, and the first recess accommodates a fused portion of the optical fiber and the GRIN lens.

An optical connector according to an embodiment of the present invention includes the ferrule described above and a plurality of optical fibers with lenses.

According to the ferrule and the optical connector of the present invention, it is possible to easily mount a lens-equipped optical fiber in which a GRIN lens is fusion-spliced at the tip of the optical fiber while suppressing an increase in optical connection loss.

FIG. 1 is an exploded perspective view showing a configuration of an optical connector according to an embodiment. FIG. 2 is a perspective view showing the first member of the main body of the ferrule shown in FIG. FIG. 3 is a top view showing a configuration of an optical connection structure including an optical connector. FIG. 4A is a sectional view taken along line IVa-IVa in FIG. FIG. 4B is a sectional view taken along the line IVb-IVb in FIG. FIG. 5 is a cross-sectional view showing the configuration of the optical connection structure shown in FIG. FIG. 6 is a perspective view showing a mold for molding the first member of the ferrule body. 7A is a perspective view showing an upper die of the die shown in FIG. 6, and FIG. 7B is a perspective view showing a lower die of the die shown in FIG. FIG. 8A is a sectional view showing an optical connector according to the first modification. FIG. 8B is a sectional view showing an optical connector according to another example of the first modification. FIG. 9 is a sectional view showing an optical connector according to the second modification. FIG. 10 is a cross-sectional view for explaining the effect of the optical connector shown in FIG. FIG. 11 is a front view showing an optical connector according to the third modification. FIG. 12 is a perspective view showing the first member of the optical connector shown in FIG. FIG. 13 is a top view showing an optical connection structure including an optical connector according to the fourth modification. 14A and 14B are cross-sectional views for explaining the problem of the ferrule according to the comparative example.

[Description of Embodiments of the Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. A ferrule according to an embodiment of the present invention includes a main body that holds a plurality of lens-equipped optical fibers in which a GRIN lens is fusion-spliced to the tip of the optical fiber, and the main body intersects the front end face of the first optical fiber. A first member including a plurality of grooves extending along the direction and arranged along a second direction intersecting the first direction; and a second member facing the plurality of grooves and separate from the first member. And the groove includes a first region that supports the optical fiber and a second region that is located between the first region and the front end face and that supports the GRIN lens, and the first member is The first recess further includes a first recess provided between the first region and the second region, and the first recess accommodates a fused portion of the optical fiber and the GRIN lens.

In this ferrule, the first member including each groove for supporting each optical fiber with lens and the second member facing each groove of the first member are separate bodies. According to this configuration, in the manufacturing process of the ferrule, the first member and the second member can be molded separately, and each groove of the first member can be formed by the mold piece instead of the core pin. In this way, unlike the case where the holding hole is formed in the ferrule, the ferrule can be molded without using the core pin of the mold, so that the bending of each groove that supports each optical fiber with lens can be suppressed. As a result, it is possible to suppress the angular deviation of the GRIN lens near the front end face, and it is possible to suppress an increase in the optical connection loss between the optical fiber with the lens and the mating optical connector.

Furthermore, the first member includes a first recess that accommodates a fused portion of the optical fiber and the GRIN lens. Accordingly, even when the fusion-bonding thickening in which the fusion-bonding portion becomes thicker than the other portions occurs, it is possible to partially secure a space that allows the fusion-bonding portion to be thick in the first member. Therefore, by mounting each optical fiber with a lens in each groove so that the fused portion is accommodated in the first recess, each optical fiber with a lens can be easily made into a ferrule without being obstructed by the fused portion. Can be implemented. Further, by letting only the thick portion of the fusion-bonded portion escape to the first concave portion in this way, the GRIN lens can be brought to the vicinity of the front end face while maintaining the length of the GRIN lens, and each groove of the first member The optical fiber with each lens can be held by the ferrule without widening the width. As a result, it is possible to suppress an increase in optical connection loss due to an optical axis shift between the optical fiber with a lens and the optical connector on the other side.

In the above ferrule, the first recess may be a linear groove extending along the second direction so as to connect the region between the first region and the second region in each groove. In this case, the shape of the mold for molding the first member is simplified as compared with the case where the first recess is formed for each groove. This can prevent the flow of the resin injected into the mold from being disturbed, so that the molding of the first member becomes easy. As a result, the ferrule is easily manufactured.

In the above ferrule, the first recess may have a rectangular shape in at least one of the cross section that intersects the first direction and the cross section that intersects the second direction. In this way, by making the cross-sectional shape of the first recess a simple shape, it becomes easy to manufacture a mold for molding the first member. This facilitates the manufacture of the ferrule.

In the above ferrule, each of the first region and the second region may have a V shape in a cross section that intersects the first direction. Accordingly, the positioning of the optical axis of each optical fiber with a lens with respect to the first member can be realized with a simple configuration. Furthermore, by making the cross-sectional shape of each of the first region and the second region simple, the mold for molding the first member can be easily manufactured, so that the ferrule can be easily manufactured.

In the above ferrule, the second member may include a second recess facing the first recess, and the second recess may accommodate a fused portion of the optical fiber and the GRIN lens. In this case, it is possible to secure a space in the second member that allows the above-mentioned fused portion to be thickened. Thereby, when pressing the lens-equipped optical fibers placed in the grooves of the first member with the second member, a gap is formed between the second member and other portions except the fused portion of the lens-equipped optical fibers. Can be suppressed. As a result, the optical fibers with lenses can be held more reliably by the ferrule body.

In the above ferrule, the first member has a U-shape that opens toward the second member in a cross section that intersects the first direction, and the second member is inside the U-shape of the first member. It may be arranged. As a result, displacement of the second member with respect to the first member in the second direction can be suppressed.

In the above ferrule, the second member has a U-shape that opens toward the first member in a cross section that intersects the first direction, and the first member is inside the U-shape of the second member. It may be arranged. As a result, displacement of the first member with respect to the second member in the second direction can be suppressed.

In the above ferrule, the first member includes a pair of guide grooves extending along the first direction at positions sandwiching the plurality of grooves and respectively supporting a pair of guide pins, and one guide groove and a plurality of grooves. And a pair of protrusions projecting toward the second member from each of the region between the other guide groove and the plurality of grooves, and the top of the pair of protrusions has a plurality of grooves. It may be located closer to the second member than the top of the space. According to this configuration, when the optical fibers with lenses are fixed to the grooves of the first member using the adhesive, the adhesive injected into the plurality of grooves is provided in a pair outside the pair of protrusions. Can be suppressed from entering the guide groove. As a result, when the ferrules are aligned with each other using the guide pins, it is possible to suppress the occurrence of positional deviation due to the adhesive entering the guide grooves, and it is possible to further suppress an increase in optical connection loss.

In the above ferrule, the main body further has an annular flange member, the first member and the second member are arranged inside the flange member, and the first member is integrally molded with the flange member. Good. When manufacturing an optical connector including this ferrule, a flange member is abutted and fixed to the housing of the optical connector. According to the above configuration, it is possible to suppress the displacement of the first member with respect to the housing against which the flange member is abutted. Accordingly, it is possible to suppress the positional deviation of the optical fibers with lenses supported in the grooves of the first member, and it is possible to further suppress an increase in optical connection loss.

The ferrule may further include a spacer provided on the front end face, and the spacer may be separate from the main body. In this case, by adjusting the thickness of the spacer, it is possible to adjust the gap with the optical fiber with lens on the other side.

The ferrule may further include a spacer protruding from the front end face, and the spacer may be integrally molded with the main body. In this case, the structure of the ferrule can be simplified and an increase in the number of parts can be suppressed.

An optical connector according to an embodiment of the present invention includes the ferrule described above and a plurality of optical fibers with lenses. Since this optical connector includes the above-mentioned ferrule, as described above, each optical fiber with a lens can be easily mounted on the ferrule, and an increase in optical connection loss between the optical connectors can be suppressed.

[Details of the embodiment of the present invention]
Specific examples of the ferrule and the optical connector according to the embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to these exemplifications, and is shown by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope. In the following description, the same elements will be denoted by the same reference symbols in the description of the drawings, and overlapping description will be appropriately omitted.

FIG. 1 is an exploded perspective view showing the configuration of the optical connector 2 according to this embodiment. An XYZ rectangular coordinate system is shown in FIG. 1 for easy understanding. In the following description, the connection direction of the optical connector 2 is the X direction (first direction), the direction orthogonal to the X direction and the arrangement direction of the plurality of optical fibers 5 with lenses is the Y direction (second direction), The Z direction is the thickness direction of the ferrule 10 that is orthogonal to the X direction and the Y direction. In addition, for convenience of description, there are cases where the direction is set to "front" or "rear" for the description. In the X direction, the mating optical connector side is the front (one side), and the opposite side is the rear (the other side).

The optical connector 2 includes a tape fiber T including a plurality of optical fibers 5 with lenses extending in the X direction, a ferrule 10 into which a front end of the tape fiber T is inserted, a front housing 20 that covers the ferrule 10, and a front housing. A rear housing 30 that engages with a rear end portion of the pin 20, a pin keeper 40 that holds a pair of guide pins P that are inserted into the ferrule 10, and a coil spring 50 that urges the ferrule 10 forward together with the pin keeper 40.

The ferrule 10 includes a main body 11 and a spacer S that is a separate body from the main body 11. The main body portion 11 holds the front end portion of each lens-equipped optical fiber 5 of the tape fiber T. The main body 11 has a substantially rectangular parallelepiped appearance extending in the X direction, and is made of, for example, resin. The main body portion 11 has a front end surface 11a and a rear end surface 11b that intersect (in one example, are orthogonal to) the X direction. The front end face 11a is arranged so as to face the optical connector on the mating side in the X direction, and the rear end face 11b is arranged on the opposite side to the front end face 11a.

The main body 11 has a lower member 13 (first member) and an upper member 14 (second member) that is separate from the lower member 13. The lower member 13 is located on one side with respect to the XY plane passing through the substantial center of the main body 11 in the Z direction, and the upper member 14 is located on the other side in the Z direction with respect to the XY plane. There is. In the present embodiment, the lower member 13 functions as a base member that supports the optical fibers 5 with lenses, and the upper member 14 functions as a lid member that holds the optical fibers 5 with lenses that are supported by the lower member 13. Function.

FIG. 2 is a perspective view showing the lower member 13. The lower member 13 has a surface 13a facing the upper member 14 (see FIG. 1) side in the Z direction, a plurality of grooves 13b extending along the X direction on the surface 13a and aligned along the Y direction, and a plurality of grooves 13b. A stepped portion 13c that is recessed from the surface 13a behind the stepped portion 13c, a stepped portion 13d that is further recessed from the stepped portion 13c behind the stepped portion 13c, and a pair of portions that extend along the X direction at a position sandwiching the plurality of grooves 13b in the Y direction. It includes a guide groove 13e. The plurality of optical fibers 5 with lenses are placed in the plurality of grooves 13b, respectively. Each groove 13b includes a first region R1 and a second region R2 located between the first region R1 and the front end face 11a. The first region R1 and the second region R2 are separated from each other in the X direction. The first region R1 extends from the step portion 13c toward the front end face 11a, and the second region R2 extends from a position separated from the front end of the first region R1 toward the front end face 11a to the front end face 11a. There is.

The lower member 13 further includes a first recess 13f provided between the first region R1 and the second region R2 in the X direction. The first recess 13f is recessed in the Z direction from the region on the surface 13a between the first region R1 and the second region R2. The first recess 13f is, for example, a linear groove extending along the Y direction so as to connect a region between the first region R1 and the second region R2 in each groove 13b, and is Y when viewed from the Z direction. It has a rectangular shape extending in the direction. The pair of guide grooves 13e are provided at positions sandwiching the plurality of grooves 13b and the first recess 13f in the Y direction, and extend in the X direction from the front end surface 11a to the rear end surface 11b. Each guide groove 13e guides each guide pin P held by the pin keeper 40.

Referring back to FIG. The main body 11 further includes an annular flange member 15 provided along the outer surface on the rear side. The flange member 15 has a lower portion 15a and an upper portion 15b that are divided with the XY plane described above (that is, the XY plane passing substantially the center of the main body 11 in the Z direction) as a boundary. The lower portion 15a is integrally molded with the lower member 13, and the upper portion 15b is integrally molded with the upper member 14.

The spacer S is provided on the front end surface 11 a of the main body 11. The spacer S has a plate shape and is made of, for example, a resin material transparent to the wavelength of light handled by the optical connector 2. The material of the spacer S may be the same as or different from that of the ferrule 10. The spacer S is joined to the front end surface 11a of the main body 11 by, for example, adhesion via an adhesive or welding (laser welding or the like).

The spacer S has a recess Sa that is recessed in the X direction from the front end surface thereof, and a pair of guide holes Sb that are provided at positions sandwiching the recess Sa in the Y direction. The recessed portion Sa has a rectangular shape extending in the Y direction when viewed from the X direction, and is provided at a position corresponding to the plurality of optical fibers 5 with lenses. The pair of guide holes Sb are respectively provided at positions corresponding to the pair of guide pins P held by the pin keeper 40.

The front housing 20 has a rectangular tubular shape extending in the X direction. The front housing 20 has an opening 20a at its front end. The ferrule 10 is inserted into the front housing 20, and the front end portion of the ferrule 10 is exposed through the opening 20a. When the ferrule 10 is inserted into the front housing 20, the flange member 15 of the ferrule 10 comes into contact with the stepped portion provided on the inner surface of the front housing 20. A latch 20b that engages with the adapter is provided on the side surface of the front housing 20. The latch 20b extends obliquely rearward from the side surface of the front housing 20.

The rear housing 30 has an insertion portion 30a inserted into the inside of the front housing 20, a rectangular plate-shaped exposed portion 30b provided at the rear end of the insertion portion 30a, and the insertion portion 30a and the exposed portion 30b penetrating in the X direction. And an insertion hole 30c through which the tape fiber T passes. The exposed portion 30b includes a protruding portion 30d that protrudes obliquely forward toward the latch 20b of the front housing 20. The protrusion 30d functions, for example, as a grip portion of the rear housing 30.

The pin keeper 40 is housed inside the front housing 20 and provided between the ferrule 10 and the coil spring 50 in the X direction. The pin keeper 40 holds a pair of guide pins P arranged along the Y direction. The pair of guide pins P are guided by the guide grooves 13e of the ferrule 10 and inserted into the guide holes Sb of the spacer S, and then inserted into the mating optical connector. Thereby, the relative alignment between the optical connector 2 and the mating optical connector is performed. The coil spring 50 urges the ferrule 10 and the pin keeper 40 toward the mating connector.

FIG. 3 is a top view showing the configuration of the optical connection structure 1 including the optical connector 2. FIG. 3 is a top view when the lower member 13 is viewed from the upper member 14 in the Z direction. In FIG. 3, the upper member 14 is omitted, and the spacer S is shown as a cross section along the XY plane that divides the lower member 13 and the upper member 14.

As shown in FIG. 3, the optical connection structure 1 includes a pair of optical connectors 2 facing each other in the X direction. In the optical connection structure 1, the spacer S of the one optical connector 2 and the spacer S of the other optical connector 2 are in contact with each other, so that the front end face 11a of the ferrule 10 of the one optical connector 2 and the other optical connector 2 are connected. The gap with the front end surface 11a of the ferrule 10 is defined. By adjusting the thickness of the spacer S of each optical connector 2 in the X direction, the gap between the front end faces 11a of the ferrules 10 of each optical connector 2 can be adjusted. In the optical connection structure 1, each of the pair of optical connectors 2 has the spacer S, but only one of the optical connectors 2 may have the spacer. In this case, since the work of joining the main body 11 and the spacer in the other optical connector 2 is unnecessary, the number of manufacturing steps of the optical connector 2 can be reduced.

Further, in each optical connector 2, the plurality of optical fibers 5 with lenses extend along the X direction and are arranged in a line along the Y direction. Each lens-equipped optical fiber 5 has an optical fiber 6 and a GRIN lens 7 fusion-spliced to the tip of the optical fiber 6. The optical fiber 6 is supported by the first region R1 of the groove 13b, and the GRIN lens 7 is supported by the second region R2 of the groove 13b. The fused portion F between the optical fiber 6 and the GRIN lens 7 is arranged in the first recess 13f. The optical fiber 6 may be a multimode optical fiber (MMF) or a single mode optical fiber (SMF). The GRIN lens 7 has a refraction distribution in which the refractive index gradually decreases from the center to the outer periphery, and is made of, for example, a transparent resin or a light transmissive material such as quartz glass. The GRIN lens 7 is optically connected to the optical fiber 6 and has the same outer diameter as the outer diameter of the optical fiber 6 (for example, 125 μm). The GRIN lens 7 extends from the tip of the optical fiber 6 to the front end surface 11 a of the main body 11.

4A is a sectional view taken along line IVa-IVa in FIG. 3, and FIG. 4B is a sectional view taken along line IVb-IVb in FIG. 4A and 4B, the upper member 14 is illustrated. As shown in FIG. 4A, the upper member 14 is arranged at a position facing each groove 13b of the lower member 13, and each optical fiber 5 with a lens mounted on each groove 13b has an upper side. It is held by the member 14. Although each optical fiber 5 with a lens is actually fixed to each groove 13b of the lower member 13 and the upper member 14 via an adhesive, in FIGS. 4(a) and 4(b), Illustration of the adhesive is omitted.

The upper member 14 includes a surface 14a that faces the surface 13a of the lower member 13 in the Z direction, and a pair of recesses 14b that are recessed from the surface 14a in the Z direction. The surface 14a is opposed to each optical fiber 5 with a lens supported by each groove 13b in the Z direction. Each recess 14b extends along the X direction so as to correspond to each guide groove 13e of the lower member 13. Each recess 14b faces each guide pin P supported by each guide groove 13e in the Z direction.

In the example shown in FIG. 4A, the surface 14 a of the upper member 14 is in contact with each optical fiber 5 with lens, and each recess 14 b of the upper member 14 is in contact with each guide pin P. .. Further, each groove 13b that supports each optical fiber 5 with a lens has a V-shape that opens toward the upper member 14 in the YZ cross section, and similarly each guide groove 13e that supports each guide pin P. Has a V-shape that opens toward the upper member 14 in the YZ cross section. The depth of each guide groove 13e with respect to the surface 13a is deeper than the depth of each groove 13b with respect to the surface 13a.

Further, as shown in FIG. 4B, the upper member 14 further includes a second recess 14c that faces the first recess 13f in the Z direction. The second recess 14c is a groove that extends linearly along the Y direction so as to correspond to the first recess 13f. Each of the first recess 13f and the second recess 14c accommodates the fused portion F. The fused portion F may have a fused thickness in which the outer diameter thereof is larger than the outer diameters of other portions. The fact that the first concave portion 13f and the second concave portion 14c accommodate the fused portion F means that the lens-attached optical fibers 5 placed in the respective grooves 13b are present even when the fused portion F is thickened by fusion. This means that the inner space of the first recess 13f and the second recess 14c allows the outer diameter of the fusion-bonded portion F to change so that the optical axis of the second recess 14c does not shift.

Therefore, the first concave portion 13f and the second concave portion 14c are formed from the outer diameter of the optical fiber with lens 5 before fusion splicing (two-dot chain line in FIG. 4B) to the optical fiber with lens after fusion splicing. When the outer diameter of the fusion-bonded portion F of No. 5 is changed, the shape is recessed from the surface 13a and the surface 14a to a position where it does not interfere with the fusion-bonded portion F where the fusion-bonding thickening occurs. As described above, the first concave portion 13f and the second concave portion 14c only need to be capable of allowing the outer diameter of the fusion-bonded portion F to change, so that the first concave portion 13f is deeper than the depth of each groove 13b with respect to the surface 13a. The depth may be shallower than the depth. The fact that the first recess 13f accommodates the fused portion F means a state in which at least a part of the fused portion F is arranged inside the first recess 13f. Similarly, the fact that the second recess 14c accommodates the fused portion F means that at least a part of the fused portion F is arranged inside the second recess 14c.

In the example shown in FIG. 4B, each of the first recess 13f and the second recess 14c has a rectangular shape in the YZ cross section. Similarly, each of the first recess 13f and the second recess 14c has a rectangular shape in the XZ cross section. The first recess 13f is recessed with respect to the surface 13a to a position deeper than the grooves 13b and shallower than the guide grooves 13e. The second recess 14c is recessed with respect to the surface 14a to the same depth as the recess 14b. Further, in the example shown in FIG. 4B, each of the first recess 13f and the second recess 14c is separated from the fused portion F, but may be in contact with the fused portion F.

The movement of light between the optical connectors 2 having the above configuration will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the configuration of the optical connection structure 1. FIG. 5 shows an XZ plane that passes through the center of each optical connector 2 in the Y direction. As shown in FIG. 5, the light L propagating in the core 6a of the optical fiber 6 of the one optical connector 2 enters the GRIN lens 7 while being expanded from the tip of the core 6a, and collimated light ( Parallel light). The light L converted into the collimated light passes through the spacer S and travels straight toward the other optical connector 2. After that, the light L passes through the spacer S of the other optical connector 2 and enters the GRIN lens 7 of the other optical connector 2. The light L incident on the GRIN lens 7 is condensed by the GRIN lens 7 on the core 6a at the tip of the optical fiber 6 and propagates in the core 6a. Thereby, the optical fiber 5 with a lens of the one optical connector 2 and the optical fiber 5 with a lens of the other optical connector 2 are optically connected.

As described above, since the numerical aperture (NA) can be reduced by enlarging the beam diameter of the light L by the GRIN lens 7, it is possible to suppress the increase of the optical connection loss due to the axis deviation and the like, and to increase the light with each lens. It is possible to realize the optical connection of the optical connectors 2 with a gap between the fibers 5. Further, by realizing the non-contact type optical connection structure 1 as described above, the adhesion of foreign matter to the front end face 11a can be reduced and the front end face 11a can be easily (or unnecessary) cleaned. Further, in the non-contact type optical connection structure 1, unlike the PC (Physical Contact) type, a large number of optical fibers 5 with lenses can be optically connected at the same time without requiring a large force for optical connection.

Subsequently, a method of manufacturing the ferrule 10 and the optical connector 2 will be described with reference to FIGS. 6, 7A, and 7B. FIG. 6 is a perspective view showing a mold 60 for molding the lower member 13 of the main body 11 of the ferrule 10. The lower member 13 is molded by resin molding using the mold 60. As shown in FIG. 6, the mold 60 has an upper mold 61 and a lower mold 62 that define a cavity.

FIG. 7A is a perspective view showing the upper mold 61 of the mold 60, and FIG. 7B is a perspective view showing the lower mold 62 of the mold 60. As shown in FIG. 7A, the upper die 61 corresponds to the bottom surface 61a corresponding to the surface 13a of the lower member 13, the plurality of protrusions 61b corresponding to the plurality of grooves 13b, and the step portion 13c. It includes a stepped portion 61c, a stepped portion 61d corresponding to the stepped portion 13d, a pair of protrusions 61e respectively corresponding to the pair of guide grooves 13e, and a convex portion 61f corresponding to the first recessed portion 13f. As shown in FIG. 7B, the lower mold 62 includes a step portion 62a corresponding to the lower portion 15a of the flange member 15.

When the lower member 13 is molded using the mold 60 having the above configuration, the upper mold 61 and the lower mold 62 are closed to each other as shown in FIG. At this time, it is preferable to fix the upper die 61 and the lower die 62 to each other. Next, molten resin is injected into the internal space formed by the upper mold 61 and the lower mold 62. After the resin in the internal space is solidified, the upper die 61 and the lower die 62 are opened to obtain the lower member 13 shown in FIG. When molding the upper member 14, the upper member 14 is molded by using a mold having a shape corresponding to the upper member 14.

Next, the optical fibers 5 with lenses are placed in the grooves 13b of the molded lower member 13. At this time, as shown in FIG. 3, the optical fiber 6 is placed in the first region R1 of the groove 13b, the GRIN lens 7 is placed in the second region R2 of the groove 13b, and the optical fiber 6 and the GRIN lens 7 are placed. The fusion-bonded portion F with is arranged in the first recess 13f. Next, an adhesive is injected onto each optical fiber with lens 5 placed in each groove 13 b, and the optical fiber 5 with lens is pressed by the upper member 14. By curing the adhesive, the optical fibers 5 with lenses are fixed to the lower member 13 and the upper member 14, and the optical connector 2 is obtained.

The effects obtained by the ferrule 10 and the optical connector 2 according to the present embodiment described above will be described together with the problems of the comparative example. 14A and 14B are cross-sectional views for explaining the problem of the ferrule 100 according to the comparative example. The difference between the ferrule 100 according to the comparative example and the ferrule 10 according to the above embodiment is the configuration of the main body of the ferrule. That is, the main body 101 of the ferrule 100 according to the comparative example is integrally molded without being divided into the lower member 13 and the upper member 14, and includes a plurality of holding holes 102 instead of the plurality of grooves 13b. There is.

The ferrule 100 having such a configuration is molded by injecting a resin into a mold having a core pin for forming the plurality of holding holes 102 and solidifying the resin. In this case, in the step of solidifying the resin, the core pin may be bent due to the contraction of the resin, and accordingly, the holding hole 102 may be bent. For example, as shown in FIG. 14A, the stress caused by the contraction of the resin acts in the direction toward the center of the main body 101 in the Y direction (the direction of the arrow in FIG. 14A), and the stress causes the solidification. Bending may occur in the rear holding hole 102. When such a bending of the holding hole 102 occurs, the posture of the optical fiber with lens 5 held in the holding hole 102 is likely to tilt. If the posture of the optical fiber with lens 5 is tilted near the front end face 11a, an angle deviation of the optical fiber with lens 5 on the front end face 11a may occur, and optical connection loss between the optical connectors 2 may increase.

Further, the main body 101 of the ferrule 100 does not have a configuration corresponding to the first recess 13f and the second recess 14c of the ferrule 10. As shown in FIG. 14B, the outer diameter of the fusion portion F is the inner diameter of the holding hole 102 (for example, 125 μm to 126 μm) due to the fusion thickening occurring in the fusion portion F between the optical fiber 6 and the GRIN lens 7. If the thickness is larger than that, it may be difficult to insert the fusion-bonded portion F into the holding hole 102. Since the length of the GRIN lens 7 is limited to a certain length in order to suppress an increase in optical connection loss, when such fusion thickening occurs, the fusion portion F interferes with the GRIN lens 7. There is a possibility that the lens 7 cannot be inserted to the tip of the holding hole 102. On the other hand, it is conceivable to make the inner diameter of the holding hole 102 larger than the outer diameter of the fused portion F, but in this case, the clearance between the holding hole 102 and the GRIN lens 7 becomes large. As a result, the GRIN lens 7 is likely to be displaced and the optical connection loss may be increased.

On the other hand, in the ferrule 10 and the optical connector 2 according to the present embodiment, the lower member 13 including the grooves 13b that support the optical fibers 5 with lenses, and the upper member that faces the grooves 13b of the lower member 13. 14 is a separate body. According to this configuration, in the manufacturing process of the ferrule 10, the lower member 13 and the upper member 14 can be molded separately, and each groove 13b of the lower member 13 is formed in the mold piece (see FIG. ) Upper mold 61). In this case, unlike the case where the holding hole 102 is formed in the ferrule 100, the ferrule 10 can be molded without using the core pin of the mold, so that the bending of each groove 13b supporting each optical fiber with lens 5 can be suppressed. As a result, the angular deviation of the GRIN lens 7 in the vicinity of the front end face 11a can be suppressed, and the increase in optical connection loss between the optical fibers 5 with lenses can be suppressed. Further, since each groove 13b and each guide groove 13e of the lower member 13 can be formed by the same piece of the mold, the relative positional accuracy between each groove 13b and each guide groove 13e is increased, and each optical fiber 5 with a lens is formed. Axis deviation can be suppressed.

Further, the lower member 13 includes a first recess 13f that accommodates the fusion-bonded portion F between the optical fiber 6 and the GRIN lens 7. As a result, even when the fusion-bonding thickening in which the fusion-bonding portion F is thicker than other portions occurs in the fusion-bonding portion F, the space for allowing the fusion-bonding portion F to be thick is partially formed in the lower member 13. Can be secured. Therefore, by mounting each optical fiber with lens 5 in each groove 13b so that the fused portion F is housed in the first recess 13f, each optical fiber with lens is not hindered by the fused portion F. 5 can be easily mounted on the ferrule 10. In addition, by allowing only the thick portion of the fusion-bonded portion F to escape to the first concave portion 13f in this way, the GRIN lens 7 can be brought to the vicinity of the front end face 11a while maintaining the length of the GRIN lens 7, and the lower side The optical fibers 5 with lenses can be held by the main body 11 of the ferrule 10 without widening the width of the grooves 13b of the member 13. As a result, it is possible to suppress an increase in optical connection loss due to an optical axis shift between the optical fiber 5 with a lens and the optical connector 2 on the other side.

In the ferrule 10 according to the present embodiment, the first recess 13f is a linear groove extending along the Y direction so as to connect the regions between the first region R1 and the second region R2 in each groove 13b. .. According to this configuration, the shape of the mold 60 for molding the lower member 13 is simplified as compared with the case where the first recess 13f is formed for each groove 13b. Thereby, the flow of the resin injected into the mold 60 can be prevented from being disturbed, so that the lower member 13 can be easily molded. As a result, the ferrule 10 can be easily manufactured.

In the ferrule 10 according to the present embodiment, the first recess 13f has a rectangular shape in the YZ cross section and the XZ cross section. In this way, by making the cross-sectional shape of the first recess 13f a simple shape, it becomes easy to manufacture the mold 60 for molding the lower member 13. This facilitates the manufacture of the ferrule 10.

In the ferrule 10 according to the present embodiment, each of the first region R1 and the second region R2 has a V shape in the YZ cross section. Accordingly, the positioning of the optical axis of each optical fiber 5 with lens with respect to the lower member 13 can be realized with a simple configuration. Furthermore, since the shapes of the cross sections of the first region R1 and the second region R2 are made simple, the mold 60 for molding the lower member 13 can be easily manufactured. Therefore, the ferrule 10 can be manufactured. Will be easier.

In the ferrule 10 according to the present embodiment, the upper member 14 includes the second recess 14c that faces the first recess 13f, and the second recess 14c accommodates the fused portion F of the optical fiber 6 and the GRIN lens 7. ing. With this configuration, it is possible to secure a space in the upper member 14 that allows the fusion-bonded portion F to be thick. With this, when the optical fibers 5 with lenses placed in the grooves 13b of the lower member 13 are pressed by the upper member 14, other portions of the optical fibers 5 with lenses other than the fused portion F and the upper member 14 are pressed. It is possible to suppress the formation of a gap between the and. As a result, it is possible to more reliably hold each lens-equipped optical fiber 5 by the main body 11 of the ferrule 10.

In the ferrule 10 according to this embodiment, the spacer S is a separate body from the main body 11. According to this configuration, by adjusting the thickness of the spacer S, it is possible to adjust the gap between the optical fiber 5 with the lens on the other side.

(First modification)
FIG. 8A is a sectional view showing an optical connector 2A according to a first modified example of the above embodiment. FIG. 8A shows a cross section corresponding to the cross section of FIG. As shown in FIG. 8A, in the present modification, the lower member 13A has a U shape that opens toward the upper member 14A in the YZ cross section, and the upper member 14A has the lower member 13A. It is arranged inside the U-shape. Specifically, the lower member 13A is configured to further include, in addition to the configuration of the lower member 13 according to the above-described embodiment, a pair of convex portions 13g protruding from both ends of the surface 13a in the Y direction. There is. Each convex portion 13g is located outside the pair of guide grooves 13e, and extends linearly along the X direction from the front end face 11a to the rear end face 11b, for example. Each protrusion 13g has, for example, a rectangular shape in the YZ cross section.

The width of the upper member 14A in the Y direction is equal to or slightly smaller than the distance between the pair of protrusions 13g in the Y direction, and is arranged between the pair of protrusions 13g in the Y direction. In the example shown in FIG. 8A, the side surface of the upper member 14A faces the inner side surface of the convex portion 13g with a slight gap in the Y direction, but is in contact with the inner side surface. Good. According to this modification, the side surface of the upper member 14A abuts on the inner surface of the pair of protrusions 13g, so that the relative movement of the upper member 14A with respect to the lower member 13A in the Y direction is restricted. Thereby, the displacement of the upper member 14A with respect to the lower member 13A in the Y direction can be suppressed.

FIG. 8B is a sectional view showing an optical connector 2B according to another example of this modification. In the example shown in FIG. 8B, the upper member 14B has a U shape that opens toward the lower member 13B in the YZ cross section, and the lower member 13B has the U shape of the upper member 14B. It is located inside. Specifically, in addition to the configuration of the upper member 14 according to the above-described embodiment, the upper member 14B further includes a pair of convex portions 14d protruding from both ends of the surface 14a in the Y direction. Each of the protrusions 14d is located outside the pair of recesses 14b, and extends linearly in the X direction from the front end face 11a to the rear end face 11b, for example. Each convex portion 14d has, for example, a rectangular shape in the YZ cross section.

The width of the lower member 13B in the Y direction is the same as or slightly smaller than the distance between the pair of protrusions 14d in the Y direction, and is arranged between the pair of protrusions 14d in the Y direction. In the example shown in FIG. 8B, the side surface of the lower member 13B is opposed to the inner side surface of the convex portion 14d with a slight gap in the Y direction, but is in contact with the inner side surface. May be. According to this modification, the side surface of the lower member 13B abuts on the inner surface of the pair of convex portions 14d, so that the relative movement of the lower member 13B with respect to the upper member 14B in the Y direction is restricted. Thereby, the displacement of the lower member 13B with respect to the upper member 14B in the Y direction can be suppressed.

(Second modified example)
FIG. 9 is a sectional view showing an optical connector 2C according to the second modification. FIG. 9 shows a cross section corresponding to the cross section of FIG. In this modification, the lower member 13C is configured to further include a pair of convex portions 13h protruding from the surface 13a in addition to the configuration of the lower member 13 according to the above-described embodiment. The pair of convex portions 13h are arranged in the Z direction from the area between the one guide groove 13e and the plurality of grooves 13b and the area between the other guide groove 13e and the plurality of grooves 13b toward the upper member 14C. Overhangs. Each convex portion 13h extends linearly along the X direction from the front end surface 11a to the rear end surface 11b, for example. Each protrusion 13h has, for example, a rectangular shape in the YZ cross section.

The tops T1 of the pair of protrusions 13h are located on the upper member 14C side in the Z direction with respect to the tops T2 between the grooves 13b. The top T1 of the protrusion 13h indicates the end of the protrusion 13h on the upper member 14C side in the Z direction. The top T2 between the grooves 13b indicates an end of the lower member 13C between the grooves 13b on the upper member 14C side in the Z direction. In the example shown in FIG. 9, the top portion T2 between the grooves 13b is included in the surface 13a. Each recess 14b of the upper member 14C extends toward the center of the upper member 14C in the Y direction so as to include a position facing each protrusion 13h in the Z direction. Each recess 14b faces (in one example, contacts) the top T1 of each protrusion 13h in the Z direction.

FIG. 10: is sectional drawing for demonstrating the effect by each convex part 13h of 13 C of lower members. As shown in FIG. 10, when manufacturing the optical connector 2C, after mounting the optical fibers 5 with lenses in the grooves 13b of the lower member 13C, the adhesive A is injected onto the optical fibers 5 with lenses. To do. At this time, by providing the pair of convex portions 13h on the outer sides of the plurality of optical fibers 5 with lenses, it is possible to suppress the adhesive A from entering the pair of guide grooves 13e provided on the outer sides of the pair of convex portions 13h. As a result, when the ferrules 10 are aligned with each other using the guide pins P, it is possible to suppress the occurrence of positional deviation due to the adhesive A entering the guide groove 13e, and it is possible to further suppress an increase in optical connection loss.

(Third modification)
FIG. 11 is a front view showing an optical connector 2D according to the third modification. In FIG. 11, the lower member 13D and the upper member 14 are shown as a YZ section. In this modification, the flange member 15A is not separated in the Z direction and is integrally molded with the lower member 13D. FIG. 12 is a perspective view showing a lower member 13D integrally molded with the flange member 15A. As shown in FIG. 12, the lower member 13D is arranged inside the annular flange member 15A, and the flange member 15A is provided on the rear portion of the lower member 13D.

As shown in FIG. 11, the width in the Y direction of the lower member 13D is the same as the width in the Y direction inside the flange member 15A, and the width in the Y direction of the upper member 14 is inside the flange member 15A. It is smaller than the width in the Y direction. The upper member 14 is arranged inside the flange member 15A, and the side surface of the upper member 14 faces the inner side surface of the flange member 15A in the Y direction with a slight gap. The width of the upper member 14 in the Y direction may be the same as the width of the inner side of the flange member 15A in the Y direction, and the side surface of the upper member 14 may be in contact with the inner side surface of the flange member 15A. ..

When manufacturing the optical connector 2D according to this modification, the flange member 15A is abutted and fixed to the stepped portion provided on the inner surface of the front housing 20 (see FIG. 1). According to this modification, since the fixed flange member 15A is integrally molded with the lower member 13D, the displacement of the lower member 13D with respect to the front housing 20 can be suppressed. As a result, it is possible to suppress the positional deviation of the optical fibers 5 with lenses supported by the grooves 13b of the lower member 13D, and it is possible to further suppress an increase in optical connection loss.

(Fourth modification)
FIG. 13 is a top view showing an optical connection structure 1A including an optical connector 2E according to a fourth modification. The top view of FIG. 13 corresponds to the top view of FIG. In this modification, the main body portion 11A of the ferrule 10A of the optical connector 2E is integrally molded with the spacer S1. The spacer S1 is an annular plate member. The spacer S1 has the same configuration as the spacer S of the above-described embodiment except for its shape. The spacer S1 projects in the X direction from the front end surface 11a of the main body 11A and surrounds a plurality of optical paths extending between the plurality of lens-equipped optical fibers 5 and the other plurality of lens-equipped optical fibers 5. Is provided. The body portion 11A is made of the same material as the spacer S1. That is, the main body 11A is made of, for example, a resin material that is transparent to the wavelength of light handled by the optical connector 2. By integrally molding the main body portion 11A and the spacer S1 in this manner, the configuration of the ferrule 10A can be simplified and an increase in the number of parts can be suppressed.

The ferrule and the optical connector according to the present invention are not limited to the above-described embodiment and each modification, and various modifications can be made. For example, the above-described embodiment and each modification may be combined with each other depending on the required purpose and effect. Further, in the above-described embodiment and each modified example, the lower member functions as a base member that supports each optical fiber with lens, and the upper member is a lid member that presses each optical fiber with lens supported by the lower member. Is functioning as. However, the lower member may function as the lid member and the upper member may function as the base member. That is, the upper member may include a plurality of grooves that support a plurality of optical fibers with lenses.

The shape of the lower member and the shape of the upper member can be changed as appropriate. For example, the upper member may not include the second recess. Further, each groove of the lower member may have another shape such as a semicircle in the YZ cross section. The first recess of the lower member and the second recess of the upper member may each have another shape such as a semicircular shape or a semielliptic shape in the YZ cross section and the XZ cross section. The first recess and the second recess may not be grooves that extend so as to connect the regions between the first region and the second region in each groove, and may be provided so as to be separated for each groove. .. When the first concave portion and the second concave portion are provided for each groove, it is sufficient that the first concave portion and the second concave portion can allow a change in the outer diameter of the fusion-bonded portion, and thus the width of each groove of the lower member in the Y direction. May be narrower than the width, and may be wider than the width.

1, 1A... Optical connection structure, 2, 2A, 2B, 2C, 2D, 2E... Optical connector, 5... Optical fiber with lens, 6... Optical fiber, 7... GRIN lens, 10, 10A... Ferrule, 11, 11A... Body part, 11a... Front end face, 13, 13A, 13B, 13C, 13D... Lower member (first member), 13b... Groove, 13e... Guide groove, 13f... First recess, 13g, 13h, 14d... Convex part , 14, 14A, 14B, 14C... Upper member (second member), 14c... Second recess, 15, 15A... Flange member, F... Fused portion, L... Light, P... Guide pin, R1... First region , R2... second region, S... spacer, T1, T2... top.

Claims (12)

The optical fiber is provided with a main body for holding a plurality of optical fibers with lenses in which a GRIN lens is fusion-spliced at the tip of
The main body is
A first member including a plurality of grooves extending along a first direction intersecting the front end face and arranged along a second direction intersecting the first direction;
A second member facing the plurality of grooves and separate from the first member;
Have
The groove includes a first region that supports the optical fiber, and a second region that is located between the first region and the front end surface and that supports the GRIN lens,
The first member further includes a first recess provided between the first region and the second region,
The first recess is a ferrule that accommodates a fusion-bonded portion of the optical fiber and the GRIN lens. The said 1st recessed part is a linear groove extended along the said 2nd direction so that the area|region in each said groove|channel between the said 1st area|region and the said 2nd area|region may be connected, It is a linear groove|channel. Ferrule. The ferrule according to claim 1 or 2, wherein the first recess has a rectangular shape in at least one of a cross section that intersects the first direction and a cross section that intersects the second direction. The ferrule according to any one of claims 1 to 3, wherein each of the first region and the second region has a V shape in a cross section that intersects the first direction. The second member includes a second recess facing the first recess,
The ferrule according to any one of claims 1 to 4, wherein the second recess accommodates the fused portion of the optical fiber and the GRIN lens. The first member has a U-shape that opens toward the second member in a cross section that intersects the first direction,
The ferrule according to any one of claims 1 to 5, wherein the second member is arranged inside the U-shape of the first member. The second member has a U-shape that opens toward the first member in a cross section that intersects the first direction,
The ferrule according to any one of claims 1 to 5, wherein the first member is arranged inside the U-shape of the second member. The first member is
A pair of guide grooves that extend along the first direction at positions sandwiching the plurality of grooves and that respectively support a pair of guide pins;
A pair of convex portions projecting toward the second member from each of the region between the one guide groove and the plurality of grooves, and the other region between the other guide groove and the plurality of grooves,
Further including,
The ferrule according to any one of claims 1 to 7, wherein the tops of the pair of convex portions are located closer to the second member than the tops between the plurality of grooves. The main body further has an annular flange member,
The first member and the second member are arranged inside the flange member,
The ferrule according to any one of claims 1 to 8, wherein the first member is integrally molded with the flange member. The ferrule further comprises a spacer provided on the front end surface,
The ferrule according to any one of claims 1 to 9, wherein the spacer is separate from the main body. The ferrule further comprises a spacer protruding from the front end surface,
The ferrule according to any one of claims 1 to 9, wherein the spacer is integrally molded with the main body portion. A ferrule according to any one of claims 1 to 11,
An optical fiber with a plurality of lenses,
Optical connector.

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