JP6268003B2 - Multi-core fiber connector and transmission device using the same - Google Patents

Description

  The present invention relates to a multi-core fiber connector that is a type of optical fiber, and a transmission device using the same, and more particularly, to an optical fiber connector including a ferrule that holds a multi-core fiber and a plug frame that houses the ferrule. .

A single-core single mode fiber (SC-SMF)) is used as a transmission medium for public network communication optical transmission systems. For example, by combining optical signals output from a plurality of semiconductor lasers with different wavelengths and propagating those signals to the SC-SMF (wavelength multiplexing method), the communication capacity can be expanded. However, with the recent diversification of broadband Internet and the spread of smartphones, and the introduction of cloud services centered on enterprises, with the explosive increase in the information transmission volume of society as a whole, light using SC-SMF Limitations are beginning to appear in transmission systems.
When the energy of the optical signal propagating through the SC-SMF exceeds several watts, the fiber breaks due to a so-called fiber fuse in which the temperature of the quartz core that is the fiber material rises and melts. Further, the transmission limit based on the nonlinear phenomenon and the theoretically transmittable communication band (Shannon limit) is 100 terabits per second (terabit: 10 12 bits), and this limit is expected to be reached around 2020. (Non-Patent Document 1).

Then, application of a multicore fiber (Multicore fiber: MCF) is examined as a solution which overcomes the above-mentioned transmission limit (nonpatent literature 2). A multi-core fiber is an optical fiber having two or more cores in a clad unlike a conventional optical fiber used in an optical transmission network.
The multi-core fiber includes a multi-core single-mode fiber (MC-SMF) and a multi-core multi-mode fiber (MC-MMF). By applying MCF, the transmitted optical signal can be distributed to multiple cores, and the optical energy density confined per core can be reduced. Therefore, it is possible to prevent fiber breakage due to the fiber fuse. Also, by using the amount of transmission signal propagating through one core in a range lower than the Shannon limit, it is possible to ensure communication quality and reliability.

  Thus, when constructing an optical communication network using MCF as a transmission line, a connector for connecting multi-core fibers to each other, a so-called connector is required.

  Patent Document 1 discloses a female ferrule for a multi-core fiber. Patent Document 2 discloses a fan-out component for a multi-core fiber having a ferrule.

JP 2008-70675 A JP 2012-208236 A

Morioka et al .: “Future innovative optical transport network technology”, NTT Technology Journal (2011.3) p. 32 Abe et al: “Physical Contact type fan-out component for 12-core multi-core fiber”, 2013 IEICE Communication Society B-13-29 (2013)

  The multi-core fiber has a plurality of cores in addition to the center of the fiber as described in FIG. For this reason, if the axial orientation of the multi-core fiber is deviated, the misalignment of each core occurs and the connection loss increases. Moreover, when the connection part of two fibers is attached / detached, since the deviation of the azimuth axis is different every time it is attached / detached, the connection loss changes. Therefore, a multi-core fiber connector with a small axial misalignment is desired.

  That is, the multi-core fiber connector needs to have a new function of suppressing azimuth misalignment as compared with a conventional single-core fiber connector. Non-Patent Documents 1 and 2 and Patent Document 1 do not have a description regarding suppression of azimuth misalignment. On the other hand, the invention of Patent Document 2 relates to a fan-out device that is one of multi-core fiber connection devices, unlike a connector that connects multi-core fibers, and therefore does not require a function to suppress azimuth misalignment. is there.

Adding a new function for suppressing azimuth misalignment to a multi-core fiber connection device is considered to be expensive.
Accordingly, an object of the present invention is to provide a multi-core fiber connecting device having an inexpensive function of preventing misalignment.

  The multi-core fiber connector of the present invention is an optical fiber connector comprising a ferrule that holds a multi-core fiber and a plug frame that accommodates the ferrule, and a pressurizing portion is provided between the ferrule and the plug frame. The ferrule has a plurality of flat surfaces on an outer periphery of one end portion, and the pressurizing unit functions as a unit that pressurizes each flat surface and suppresses a deviation in the axial direction of the multicore fiber. It is characterized by doing.

  The optical fiber connector of the present invention can suppress azimuth misalignment (rotation of the central axis) of the multicore fiber by pressurizing the outer flat surface of the ferrule that accommodates the multicore fiber from a plurality of directions. That is, by providing a plurality of flat surfaces on the outer periphery of the ferrule and pressurizing the flat surfaces using the pressurizing unit, it is possible to prevent the azimuth axis deviation of the multicore fiber. In addition, by using an integrated pressure spring as the pressure unit, it is possible to mount a pressure spring by simply reworking a conventional single core fiber connector, and an inexpensive multi-core fiber optic connector. Can be provided.

Sectional drawing of the connector for multi-core fibers based on Example 1 of this invention. The conceptual diagram which shows the AB cross section of FIG. The front view and side view of a leaf | plate spring structure for hold | maintaining the ferrule of Example 1. FIG. The conceptual diagram of one method of connecting two multi-core fibers using the connector for multi-core fibers of Example 1. FIG. The conceptual diagram of the other method which connects two multi-core fibers using the connector for multi-core fibers of Example 1, and a lens array based on Example 2 of this invention. The conceptual diagram of the optical transmission apparatus using the multi-core fiber connector based on Example 3 of this invention.

The present invention basically suppresses the azimuth misalignment (rotational misalignment of the central axis) of the multicore fiber by pressurizing the side surface of the ferrule accommodating the multicore fiber from a plurality of directions. Specifically, by providing a flat surface on the outer periphery of one end of the ferrule and pressurizing the flat surface of the ferrule using the pressurizing unit, it is possible to suppress the azimuth misalignment of the multicore fiber. Furthermore, by using an integrated pressure spring as the pressure portion, the pressure spring can be mounted only by performing additional processing on the conventional single core fiber connector.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The multicore fiber connector according to the first embodiment of the present invention is an optical fiber connector including a ferrule that holds a multicore fiber and a plug frame that accommodates the ferrule, and the ferrule is disposed on an outer periphery of one end. The plug frame has a plurality of flat surfaces, the plug frame has a pressurizing portion for pressurizing the flat surface, and the other end of the ferrule is inserted into the split sleeve. The multi-core fiber connector of Example 1 will be described with reference to FIGS. 1, 2, 3, and 4. FIG.

  FIG. 1 shows a cross-sectional structure of the connector for multicore fiber according to the first embodiment. FIG. 2 is a schematic view of the A-B cross section of FIG. FIG. 3 is a side view (a) and a front view (b) of a leaf spring structure for holding a ferrule.

  As shown in FIG. 1, the multicore fiber connector 1 of the present invention basically includes a ferrule 3 that holds the multicore fiber 2, a plug frame 4 that accommodates the ferrule 3, and a shaft that is common to the ferrule 3. It is composed of a ferrule flange 5 located on the top and a leaf spring structure 7. In the example of FIG. 1, the flange 5 is separate from the ferrule 3, but both may be integrated. In other words, the ferrule 3 of the present invention includes a ferrule body that holds the multi-core fiber 2 and a ferrule flange 5 that is formed at one end portion 12 of the ferrule body.

  The multi-core fiber 2 is an optical fiber having two or more cores in one fiber. The multi-core fiber 2 may not necessarily have a core arranged in a triangular lattice shape having a core at a general center. For example, the cores may be arranged in a square lattice shape. The main body of the ferrule 3 is a container for accommodating a part of the multi-core fiber 2 therein. Usually, the ferrule is provided in the one end part 12 of the multi-core fiber 2, and is used in order to optically connect with another optical fiber.

  The main body of the ferrule 3 may be composed of one member or may be composed of two or more parts. In the example shown in FIG. 1, a ferrule flange 5 is provided so as to be pressed by a coil spring 6 at one end portion 12 of a substantially cylindrical ferrule body. The ferrule flange 5 includes a small-diameter portion where the coil spring 6 is installed on the outside and a large-diameter portion where the pressurizing portion is installed on the outside. That is, a plurality of flat surfaces are provided on the outer peripheral surface of the large-diameter portion of the ferrule flange 5, and the flat surfaces are uniformly pressed by a pressurizing portion (for example, a leaf spring structure 7). Thereby, a pressurizing part functions as a means for suppressing a shift in the axial direction of the multi-core fiber.

  As shown in FIG. 2, the ferrule in the multicore fiber connector of the present invention has flat surfaces 8 on the four side surfaces of the outer periphery of the ferrule flange 5 having a rectangular longitudinal section. This flat surface may be approximately flat.

  In this embodiment, one end portion 12 of the main body of the ferrule 3 is inserted into the large diameter portion of the ferrule flange 5 and fixed with an adhesive or the like. The ferrule flange 5 has four flat surfaces 8 (8a, 8b, 8c, and 8d) at 90-degree rotationally symmetric positions. In the plug frame 4, a plate-like portion that extends in the axial direction and pressurizes the flat surfaces 8 a, 8 b, 8 c, 8 d with the equal force P, that is, the pressurizing portion 9 (9 a, 9 b). 9c, 9d). An arrow described in the pressurizing unit in FIG. 2 indicates the pressurizing direction of the force P.

  FIG. 3 shows a structural diagram (front view = (a)) and side view = (b) of a plate spring structure type pressure unit 9 as an example of the pressure unit. The leaf spring structure 7 includes a metallic cylindrical base portion sandwiched between the main body of the ferrule 3 and the large-diameter portion of the ferrule flange 5, a branch portion extending from one end of the base portion, and extending radially outward. It has a structure in which four pressing portions (plate springs) 9 formed on the outer periphery and press-fitting holding projections 10 are integrated. The pressurizing unit 9 is configured to be pressed by the inner peripheral surface of the plug frame 4 and to have its tip portion pressed against the flat surface 8 of the ferrule flange 5.

  By using the leaf spring structure 7, it is possible to easily produce the pressurizing portions 9 a, b, c, and d in the existing plug frame 4.

  The press-fitting holding projection 10 is provided to engage with the groove on the inner periphery of the corner of the ferrule flange 5 so that the leaf spring structure 7 is not displaced with respect to the plug frame 4.

  The longitudinal section of the large diameter portion of the ferrule flange 5 may be another polygon (pentagon or hexagon), and a flat surface may be formed on each side. Alternatively, the large-diameter portion may be a circular longitudinal section, and a plurality of flat surfaces may be formed on the outer peripheral portion.

  In this way, by pressing the outer peripheral surface of the ferrule that accommodates the multi-core fiber evenly from a plurality of directions, it is possible to suppress the azimuth misalignment (rotation shift of the central axis) of the multi-core fiber. That is, by providing a plurality of flat surfaces on the outer periphery of the ferrule and pressurizing the flat surfaces evenly using a pressurizing unit, it is possible to prevent azimuth misalignment of the multicore fiber. In addition, by using an integral leaf spring as the pressure unit, a pressure spring can be mounted by simply reworking the conventional single core fiber connector, providing an inexpensive multi-core fiber optic connector. can do.

  FIG. 4 is a conceptual diagram for connecting two multi-core fibers using the multi-core fiber connector of the present invention.

  In the preferred multi-core fiber connector 1 of the present invention, the other end portion 11 of the ferrule 3 is inserted into the split sleeve 13. Then, by inserting the other end portion 11 of another multi-core fiber connector 1 from the opposite side of the split sleeve 13, the two multi-core fibers 1 and 1 can be connected. The split sleeve 13 accommodates the ferrules 3 and 3 of the two multi-core fiber connectors so as to closely contact each other, thereby optically connecting the cores included in the two multi-core fibers and maintaining the connection state. It is an optical component.

  The inside of the split sleeve 13 has, for example, a shape corresponding to the outer periphery of the other end portion 11 of the ferrule 3. For this reason, the split sleeve 13 can hold the two ferrules 3 stably. A multi-core fiber connector is inserted into each of the two ends of the split sleeve 13, and the multi-core fibers housed in the respective multi-core fiber connectors are brought into close contact with each other. In this way, the cores included in the multicore fiber are optically connected.

  According to the present embodiment, an inexpensive optical fiber connector for a multi-core fiber can be provided.

  A multi-core fiber connector according to a second embodiment of the present invention is an optical fiber connector including a ferrule that holds a multi-core fiber and a plug frame that accommodates the ferrule, and the multi-core fiber includes a core portion, Each core part of the multi-core fiber having a clad part and accommodated in the pair of multi-core fiber connectors is optically connected by a microlens array at the other end of the ferrule.

  One connection method shown in FIG. 4 is a so-called physical contact method in which end portions of ferrules are abutted. In this method, in order to reduce the connection loss, it is not necessary to polish the ferrule end (that is, the end face of the multicore fiber) with high accuracy. This polishing accuracy is said to deteriorate as the number of cores increases (especially when the number of cores is 8 or more) (Non-Patent Document 2).

Therefore, in this embodiment, as another connection method, the microlens array 15 is inserted between the two ferrules 3 and 3. The multi-core fiber connector of Example 2 will be described with reference to FIG. FIG. 5 shows a conceptual diagram of the second embodiment. Reference numeral 200 denotes a core part of the multicore fiber, and 300 denotes a clad part of the multicore fiber. The pair of left and right ferrules 3 are fixed in relative positional relationship by another member (not shown). By connecting the pair of ferrules 3 and 3 with a microlens array, the polishing accuracy required to obtain an equivalent connection loss is reduced as compared with the case of physical contact. An example of the microlens array 15 is a refractive index matching lens type microlens array using a nanoimprint technique.

  According to the present embodiment, it is possible to provide a cheaper optical fiber connector for a multi-core fiber.

  An optical transmission apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. This optical transmission apparatus has optical fiber adapters 17 and 20 for inserting the multi-core fiber connector 1 of the first or second embodiment on the surfaces of the patch panel 16 and the interface panel 19 for accommodating optical fiber wiring. . That is, the multi-core fiber connector 1 of the first or second embodiment is used between the multi-core fiber bundle 18 and the optical fiber adapter 17 and between the multi-core fiber bundle 18 and the optical module mounting optical fiber adapter 20. Yes. An optical module is mounted inside the transmission device casing 21.

  Usually, there is a patch panel portion for adjusting the length of an optical fiber routed from an external optical communication network, absorbing the extra length portion, and arranging the optical fiber wiring. When a single core fiber is used, with the increase in transmission capacity in recent years, the number of optical fibers and the number of optical fiber adapters 17 and 20 on the patch panel surface increase, and the increase in the area of the patch panel or the like becomes a problem. ing.

Therefore, as shown in FIG. 6, the use of the multicore fiber bundle 18, the multicore fiber connector 1, and the multicore fiber connector optical fiber adapters 17, 20 eliminates the problem of an increase in the area of the patch panel 16 and the interface panel 19. Can be solved.

DESCRIPTION OF SYMBOLS 1 Multicore fiber connector 2 Multicore fiber 3 Ferrule 4 Plug frame 5 Ferrule flange 6 Coil spring 7 Leaf spring structure 8 (8a, 8b, 8c, 8d) Flat surface 9 (9a, 9b, 9c, 9d) Pressurizing part 10 Press fit Holding projection 11 Other end portion 12 of ferrule One end portion 13 of ferrule 13 Split sleeve 15 Micro lens array 16 Patch panel 17 Optical fiber adapter 18 Multi-core fiber bundle 19 Interface panel 20 Optical module mounted optical fiber adapter 21 Transmission device housing 200 Core part 300 Clad part.

Claims (9)

A multicore fiber connector comprising a ferrule for holding a multicore fiber and a plug frame for housing the ferrule,
A pressure unit is provided between the ferrule and the plug frame,
The ferrule has a plurality of flat surfaces on the outer periphery of one end portion,
The pressurizing unit pressurizes each flat surface and functions as a means for suppressing a deviation in the axial direction of the multicore fiber ,
The multi-core fiber connector, wherein the pressurizing unit is configured by a leaf spring structure in which the same number of pressurizing springs as the plurality of flat surfaces are integrated . In claim 1 ,
The ferrule is
A ferrule body holding the multi-core fiber;
Having a ferrule flange located on a common axis with the ferrule;
The multi-core fiber connector, wherein the plurality of flat surfaces are formed on an outer peripheral surface of the ferrule flange. In claim 2 ,
The leaf spring structure is
A metallic cylindrical base sandwiched between the ferrule body and the ferrule flange;
A plate-like portion extending from one end of the base portion radially outward and formed on the outer periphery of the ferrule flange and extending in a branching direction in the axial direction to be the plurality of pressurizing portions;
The multi-core fiber connector, wherein the leaf spring structure is configured to be pushed by an inner peripheral surface of the plug frame so that the plate-like portion is pressed against a flat surface of the ferrule flange. In claim 3 ,
The connector for a multi-core fiber, wherein the leaf spring structure has a press-fit holding projection for press-fitting into the plug frame. In claim 3 ,
The ferrule flange has a small-diameter part where a coil spring is installed on the outside, and a large-diameter part where the pressurizing part is installed on the outside.
The plurality of flat surfaces are provided on the outer peripheral surface of the large-diameter portion of the ferrule flange,
Inside the large diameter part of the ferrule flange, one end portion of the main body of the ferrule is inserted and fixed,
The multi-core fiber is configured such that the plate-like portion at the tip of the leaf spring structure is pushed by the inner peripheral surface of the plug frame and is pressed against the flat surface of the ferrule flange with an equal force. Connector. In claim 1 ,
A multi-core fiber connector, wherein the other end of the ferrule is inserted into a split sleeve . A multicore fiber connector comprising a ferrule that holds a multicore fiber and a plug frame that houses the ferrule,
The multi-core fiber has a core part and a clad part,
A pressure unit is provided between the ferrule and the plug frame,
Having a plurality of flat surfaces on the outer periphery of one end of the ferrule;
The pressurizing unit pressurizes each flat surface and functions as a means for suppressing a deviation in the axial direction of the multicore fiber,
An optical fiber connector characterized in that each core part of the multi-core fiber accommodated in a pair of multi-core fiber connectors is optically connected by a microlens array at the other end of the ferrule. . An optical transmission device in which an optical module is mounted inside a housing,
On the patch panel surface for optical fiber wiring accommodation, it has an optical fiber adapter,
The flux lines of the multicore fiber and between the optical fiber adapter, the optical transmission device, characterized in that there is the multi-core fiber connector according to any one of claims 1 to 7. In claim 8 ,
On the interface panel surface for accommodating the optical fiber wiring, an optical module mounted optical fiber adapter is provided,
An optical transmission apparatus comprising the multi-core fiber connector between the multi-core fiber bundle and the optical module-mounted optical fiber adapter.

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