1. Field of the Invention
The present invention relates to an optical fiber connecting method for optically connecting a multicore fiber to a single-core fiber and an optical fiber connecting structure.
2. Related Background Art
Techniques for optically connecting a multicore fiber, which comprises a plurality of cores each extending along a predetermined axis and a cladding integrally surrounding the plurality of cores, to a single-core fiber, which comprises a core extending along a predetermined axis and a cladding surrounding the core, have been known (see, for example, Japanese Patent Application Laid-Open No. 57-210313).
For connecting a multicore fiber, which has recently been made with a very fine diameter and ultrahigh density, to a plurality of single-core fibers, it is necessary to connect a plurality of cores at their correct positions between the multicore fiber and the plurality of single-core fibers. When sufficient accuracy cannot be attained in positioning in connected parts at the time of connecting cores to each other, their loss may increase, thereby lowering efficiency.
For solving the problem mentioned above, it is an object of the present invention to provide an optical fiber connecting method and optical fiber connecting structure which can efficiently connect a multicore fiber to a plurality of single-core fibers.
For solving the above-mentioned problem, the optical fiber connecting method in accordance with the present invention is an optical fiber connecting method for connecting a multicore fiber, constituted by a plurality of cores and a cladding integrally surrounding the plurality of cores, to a single-core fiber constituted by a single core and a cladding surrounding the core; the method comprising a first step of preparing a first connection member for holding the multicore fiber, positioning the multicore fiber in the first connection member, and then fixing the multicore fiber to the first connection member; a second step of preparing a second connection member for holding a plurality of single-core fibers, positioning the single-core fibers such that the single cores are arranged at respective positions corresponding to arrangements of the plurality of cores in the multicore fiber, and then fixing the plurality of single-core fibers to the second connection member; and a third step of positioning and joining the first and second connection members such that the plurality of cores face the respective single cores, so as to connect the multicore fiber to the plurality of single-core fibers.
This optical fiber connecting method connects a multicore fiber to a plurality of single-core fibers by using first and second connection members. The multicore fiber is fixed to the first connection member after being positioned therein. The plurality of single-core fibers are positioned such that the cores are arranged at respective positions corresponding to arrangements of cores in the multicore fiber and then fixed to the second connection member. Thereafter, the first and second connection members are joined to each other, so as to connect the multicore fiber to a plurality of single-core fibers. Since the multicore fiber and single-core fibers are thus connected to each other after being positioned individually, the cores can be butted against each other with high accuracy, whereby the loss can be reduced. As a result, a multicore fiber can efficiently be connected to a plurality of single-core fibers.
The multicore fiber may have the plurality of cores arranged at equally-spaced intervals in a cross-section thereof, while the single core fiber may be configured such that at least a leading end part of the cladding has an outer diameter equal to an interval between the plurality of cores.
The first connection member has a fiber insertion hole for inserting the multicore fiber and a guide hole for inserting a guide pin, the second connection member has a positioning part for defining the arrangements of the single-core fibers so as to place the single cores in the single-core fibers at positions corresponding to the arrangements of the plurality of cores in the multicore fiber and a guide part for inserting the guide pin, and the guide pin joins the first and second connection members to each other in the third step. This mode allows the guide pin to position the first and second connection members accurately.
The plurality of cores are arranged axially symmetrically at equally-spaced intervals, the first connection member is provided with at least two guide holes, the two guide holes being arranged such that the fiber insertion hole is located therebetween, and the first step axially rotates and positions the multicore fiber with respect to the first connection member such that the arrangements of the plurality of cores form a predetermined angle with a line connecting respective center axes of the two guide holes. This mode can favorably position the multicore fiber.
The second connection member is provided with at least two guide parts, the two guide parts being arranged such that the positioning part is located therebetween, and the second step arranges the single-core fibers at the positioning part, so as to position the plurality of single-core fibers. This mode can favorably achieve a two-dimensional array of the single-core fibers.
The second connection member comprises a first part formed with the positioning part and guide part and a second part for holding the plurality of single-core fibers with the first part. The second connection member comprises a first part formed with a first positioning part constituting the positioning part and a first guide part constituting the two guide parts and a second part formed with a second positioning part constituting the positioning part while being arranged so as to oppose the first positioning part and a second guide part constituting the two guide parts while being arranged so as to oppose the first guide part, and the single-core fiber is held by the first and second parts.
The positioning part has a substantially V-shaped cross-section. Alternatively, the positioning part has a cross-section exhibiting a form corresponding to an outer form of a bundle of the plurality of single-core fibers. Such a mode can position the single-core fibers easily and appropriately.
The first connection member comprises a cylindrical ferrule having a fiber insertion hole for inserting the multicore fiber and an accommodation member for accommodating the ferrule, and the first step axially rotates and positions the multicore fiber such that the arrangements of the plurality of cores form a predetermined angle with a line connecting a predetermined position of the accommodation member and a center axis of the fiber insertion hole. This mode can favorably position the multicore fiber.
The plurality of cores are arranged axially symmetrically at equally-spaced intervals, the accommodation member is provided with a projection projecting radially out of the ferrule, and the first step axially rotates and positions the multicore fiber such that the arrangements of the plurality of cores form a predetermined angle with a line connecting the projection and the center axis of the fiber insertion hole. This mode can favorably position the multicore fiber.
The second connection member has a positioning part for defining the arrangements of the single-core fibers so as to place the single cores in the single-core fibers at positions corresponding to the arrangements of the plurality of cores in the multicore fiber, and the second step arranges the single-core fibers at the positioning part, so as to position the plurality of single-core fibers. This mode can favorably achieve a two-dimensional array of the single-core fibers.
The positioning part has a substantially V-shaped cross-section. Alternatively, the positioning part has a cross-section exhibiting a form corresponding to an outer form of a bundle of the plurality of single-core fibers. Such a mode can position the single-core fibers easily and appropriately.
The second connection member comprises a cylindrical ferrule including a fiber insertion hole, having an inner diameter substantially equal to an outer size of the plurality of single-core fibers, for inserting the plurality of single-core fibers, and the second step inserts and positions the plurality of single-core fibers in the fiber insertion hole. This mode can favorably achieve a two-dimensional array of the single-core fibers.
The fiber insertion hole of the ferrule has a greater bore on one end side for inserting the plurality of single-core fibers therefrom than on the other end side. Such a mode can insert a plurality of optical fibers into the fiber insertion hole easily and appropriately.
The optical fiber connecting structure in accordance with the present invention is an optical fiber connecting structure connecting a multicore fiber, constituted by a plurality of cores and a cladding integrally surrounding the plurality of cores, to a single-core fiber constituted by a single core and a cladding surrounding the core; the optical fiber connecting structure comprising a first connection member for holding the multicore fiber and a second connection member for holding a plurality of single-core fibers, the first connection member positioning and fixing the multicore fiber, the second connection member arranging the single cores at respective positions corresponding to the arrangements of the plurality of cores in the multicore fiber and fixing the plurality of single-core fibers, the first and second connection members being positioned and joined to each other such that the plurality of cores face the respective single cores.
The multicore fiber may have a plurality of cores arranged at equally-spaced intervals in a cross-section thereof, while the single core fiber may be configured such that at least a leading end part of the cladding has an outer diameter equal to an interval between the plurality of cores.
The first connection member has a fiber insertion hole for inserting the multicore fiber and a guide hole for inserting a guide pin, the second connection member has a positioning part for defining the arrangements of the single-core fibers so as to place the single cores in the single-core fibers at positions corresponding to the arrangements of the plurality of cores in the multicore fiber and a guide part for inserting the guide pin, and the guide pin joins the first and second connection members to each other.
The second connection member comprises a first part formed with the positioning part and guide part and a second part for holding the plurality of core fibers with the first part.
The second connection member comprises a first part formed with a first positioning part constituting the positioning part and a first guide part constituting the two guide parts and a second part formed with a second positioning part constituting the positioning part while being arranged so as to oppose the first positioning part and a second guide part constituting two guide parts while being arranged so as to oppose the first guide part, and the single-core fiber is held by the first and second parts.
The positioning part has a substantially V-shaped cross-section. Alternatively, the positioning part has a cross-section exhibiting a form corresponding to an outer form of a bundle of the plurality of single-core fibers.
The first connection member comprises a cylindrical ferrule having a fiber insertion hole for inserting the multicore fiber and an accommodation member for accommodating the ferrule.
The second connection member has a positioning part for defining the arrangements of the single-core fibers so as to place the single cores in the single-core fibers at positions corresponding to the arrangements of the plurality of cores in the multicore fiber.
The positioning part has a substantially V-shaped cross-section. Alternatively, the positioning part has a cross-section exhibiting a form corresponding to an outer form of a bundle of the plurality of single-core fibers.
The second connection member comprises a cylindrical ferrule including a fiber insertion hole, having an inner diameter substantially equal to an outer size of the plurality of single-core fibers, for inserting the plurality of single-core fibers.
The fiber insertion hole of the ferrule has a greater bore on one end side for inserting the plurality of single-core fibers therefrom than on the other end side.
The present invention can connect a multicore fiber to a plurality of single-core fibers efficiently with high accuracy.
a) is a view of a ferrule as seen from the front side, while
In the following, preferred embodiments of the present invention will be explained in detail with reference to the accompanying drawings. In the explanation of the drawings, the same or equivalent constituents will be referred to with the same signs, while omitting their overlapping descriptions.
As illustrated in
First, the MCF 1 and SCF 5 will be explained. As illustrated in
Returning to
The MCF insertion hole 14 is a through hole extending in a direction in which a front end face 12a of the MT ferrule 12 and a rear face thereof (not depicted) oppose each other. The MCF 1 is inserted into the MCF insertion hole 14 from the rear side of the MT connector 10. The MCF 1 is secured to the MCF insertion hole 14 with an adhesive, for example. An end face 1a of the MCF 1 and the front end face (connection end face) 12a of the MT ferrule 12 are substantially flush with each other. The diameter of the MCF insertion hole 14 is made substantially equal to or slightly greater than the outer diameter of the MCF 1.
The guide holes 16a, 16b are arranged such that the MCF insertion hole 14 is located therebetween. A line L connecting center axes Ax1, Ax2 of the two guide holes 16a, 16b to each other passes a center axis Ax3 of the MCF insertion hole 14. That is, the center axes Ax1, Ax2 of the two guide holes 16a, 16b are placed on the same line L1 as with the center axis Ax3 of the MCF insertion hole 14. Respective columnar guide pins P are inserted in the guide holes 16a, 16b so as to project from the front end face 12a of the MT ferrule 12.
As illustrated in
The first holding part 24 is formed with an SCF positioning groove (positioning part) 28 and guide grooves (guide parts) 30a, 30b. The SCF positioning groove 28 has a substantially V-shaped cross-section forming an angle of about 60°. A plurality of (10 here) SCFs 5 are arranged in ranks in the SCF positioning groove 28. With the second holding part 26, the SCF positioning groove 28 forms an SCF insertion hole for inserting the SCFs 5.
The guide grooves 30a, 30b are arranged such that the SCF positioning groove 28 is located therebetween. Each of the guide grooves 30a, 30b has a substantially V-shaped cross-section. With the second holding part 26, the guide grooves 30a, 30b define guide holes for inserting the guide pins P. The guide grooves 30a, 30b may have circular cross-sections in conformity to the (columnar) forms of the guide pins P.
The SCF positioning groove 28 is formed by molding with glass or a resin, cutting of the first holding part 24 (substrate) with a V-shaped blade, etching of the first holding part 24 made of silicon, or the like. When the SCF positioning groove 28 is formed by molding or cutting with a blade, its bottom may become a curved surface as illustrated in
By contrast, as illustrated in
A method of connecting the MCF 1 to a plurality of SCFs 5 will now be explained.
First, the MT ferrule 12 is prepared, and the MCF 1 is inserted into the MCF insertion hole 14 from the rear side of the MT ferrule 12. After being inserted 1 into the MCF insertion hole 14, the MCF 1 is axially rotated with respect to the MT ferrule 12 as illustrated in
After being positioned, the MCF 1 is secured to the MT ferrule 12 with an adhesive. Then, the end face 1a of the MCF 1 is polished.
Subsequently, the MT ferrule 22 is prepared, and the SCFs 5 are arranged in the positioning groove 28. Specifically, as illustrated in
Next, the MT ferrules 12, 22 are caused to oppose each other, and the guide pins P inserted in the guide holes 16a, 16b of the MT ferrule 12 are introduced into the guide holes 30a, 30b of the MT ferrule 22, respectively. Subsequently, the end face 1a of the MCF 1 and the end face 5a of the SCF 5 are caused to oppose each other, so that the MCF 1 is optically connected to a plurality of SCFs 5 (third step).
In this embodiment, as explained in the foregoing, the MCF 1 is connected to the plurality of SCFs 5 through the MT connectors 10, 20. The MCF 1 is axially rotated so as to be positioned with respect to the MT ferrule 12 and then is secured thereto. The plurality of SCFs 5 are positioned by the positioning groove 28 of the MT ferrule 22 so as to arrange the cores 6 at the respective positions corresponding to the arrangements of the cores 2a to 2g in the MCF 1 and then are fixed to the MT ferrule 22. Subsequently, the MT connectors 10, 20 are joined to each other, so as to connect the MCF 1 to the plurality of SCFs 5. The MCF 1 and SCFs 5 are thus positioned and connected, so that their cores 2a to 2g, 6 can be butted against each other with high accuracy, whereby the loss can be reduced. As a result, the MCF 1 can be connected to the SCFs 5 efficiently.
Since the positional groove 28 has a V-shaped cross-section, this embodiment can arrange a plurality of SCFs 5 in the positioning groove 28 and thus can favorably position the SCFs 5.
Other modes of the MT ferrule 22 will now be explained with reference to
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
In thus constructed MT ferrule 22H, the SCFs 5 are juxtaposed with each other at intervals of about 47 μm, for example, in the depicted horizontal line in each of the first and second holding parts and arranged with a gap of about 90 μm, for example, therebetween in the depicted vertical direction. That is, the SCF 5 are not arranged at equally-spaced intervals in the MT ferrule 22H. Therefore, a plurality of cores are not arranged at equally-spaced intervals in a cross-section of the MCF held by the MT ferrule 12 joined to the MT ferrule 22H. Thus, a plurality of cores may be arranged at equally-spaced intervals or not in a cross-section of the MCF 1 in this embodiment.
The second embodiment will now be explained.
As illustrated in
a) is a view of the ferrule as seen from the front side, while
As illustrated in
The projection 45 is also used as a reference for positioning arrangements of cores 2a to 2g of the MCF 1. That is, when being positioned, the MCF 1 is rotated with respect to the ferrule 42 such that the arrangements of the cores 2a to 2g in the MCF 1 form a predetermined angle with a line L1 connecting the projection (predetermined position) 45 and the center axis of the MCF insertion hole 42a in the state where the ferrule 42 is accommodated in the housing 44 as illustrated in
The FC connector 50 comprises a cylindrical ferrule 52 for holding the SCFs 5, a first housing 54 for accommodating the ferrule 52, and a second housing 56 disposed on the rear end side of the second housing 54.
As illustrated in
A method of connecting the MCF 1 to a plurality of SCFs 5 will now be explained.
First, the ferrule 42 is prepared, and the MCF 1 is inserted into the ferrule insertion hole 42a from the rear side of the ferrule 42. After being inserted 1 into the MCF insertion hole 42a, the MCF 1 is axially rotated with respect to the ferrule 42 as illustrated in
After being positioned, the MCF 1 is secured to the ferrule 42 with an adhesive. Then, the end face la of the MCF 1 is polished.
Subsequently, the ferrule 52 is prepared, and the SCFs 5 are inserted into the SCF insertion hole 52a. Specifically, as illustrated in
Next, the ferrules 42, 52 are caused to oppose each other, and the projections 45, 55 of the housings 44, 54 are inserted into the guide grooves 60a, 60b of the FC adapter 60, respectively. Subsequently, the end face 1a of the MCF 1 and the end face 5a of the SCF 5 are caused to oppose each other, so that the MCF 1 is optically connected to a plurality of SCFs 5 (third step).
In this embodiment, as explained in the foregoing, the MCF 1 is connected to the plurality of SCFs 5 through the FC connectors 40, 50. The MCF 1 is axially so as to be positioned with respect to the ferrule 42 and then is connected thereto. The plurality of SCFs 5 are positioned in the ferrule 52 so as to arrange the cores 6 at the respective positions corresponding to the arrangements of the cores 2a to 2g in the MCF 1 and then are fixed to the ferrule 52. Subsequently, the FC connectors 40, 50 are joined to each other through the FC adapter 60, so as to connect the MCF 1 to the plurality of SCFs 5. The MCF 1 and SCFs 5 are thus positioned and connected, so that their cores 2a to 2g, 6 can be butted against each other with high accuracy, whereby the loss can be reduced. As a result, the MCF 1 can be connected to the SCFs 5 efficiently.
Since the MCF 1 is positioned by using the projection 45 provided with the housing 44, the arrangements of the cores 2a to 2g can attain a predetermined angle easily and accurately in this embodiment. Therefore, the MCF 1 can be positioned easily and reliably.
The present invention is not limited to the above-mentioned embodiments. For example, the ferrule 52 may be configured as follows in the second embodiment.
While the second embodiment positions the SCFs 5 by inserting them into the SCF insertion hole 52a in the ferrule 52, the SCFs 5 may be positioned by using a ferrule formed with a positioning groove as in the ferrule illustrated in the first embodiment.
While the second embodiment provides the housing 44 with the projection 45, by which the FC connector 40 is positioned in the FC adapter 60, other structures (such as depressions and orientation flats) may be used for positioning the FC connector 40 in the FC adapter 60. Though the projection 45 is also used as a predetermined position for a reference for positioning the arrangements of the cores 2a to 2g in the MCF 1, forms other than the projection 45 may also be used as the reference for positioning.
Number | Date | Country | Kind |
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2011-135212 | Jun 2011 | JP | national |