JP2016133516A - Multi-core fiber connection device and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-fiber connection device for connecting multi-core fibers with each other without branching one length of multi-core fiber into a plurality of conventional single-core fibers.SOLUTION: A connection device 50 has: first optical systems 51, 52 for converting light transmitted from the first number of cores 1-12 of a first optical fiber 100 into a first number of parallel beam groups; a conversion optical system 60 for moving at least a portion of the first number of parallel beam groups in parallel without changing the direction of an optical axis; second optical systems 53, 54 for forming the image a second parallel beam or a second parallel beam group that is a portion of the first number of parallel beam groups having passed through the conversion optical system in the core of a second optical fiber 200; and third optical systems 55, 56 for forming the image a third parallel beam or a third parallel beam group that is the other portion of the first number of parallel beam groups having passed through the conversion optical system in the core of a third optical fiber 300.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a multi-core fiber connection device, and relates to a device for optically connecting a single multi-core fiber and a plurality of optical fibers including at least two multi-core fibers having a different number of cores from the multi-core fiber. Concerning configuration.

  As a result of the broadbandization of application services using optical fiber communications, the amount of Internet traffic has grown at a rate approximately twice as high in two years, and this trend is expected to continue. In the future, in addition to relatively long networks of several kilometers or more such as backbone, metro, and access systems, information communication (ICT) equipment such as servers in data centers (a few meters to a few hundred meters) or within equipment ( Even for extremely short distances (several centimeters to several tens of centimeters), it is considered that the signal wiring is switched from electrical wiring to optical wiring that can realize high speed and low power consumption.

  With regard to further increase in capacity, the limit has begun to appear in the increase in communication capacity by wavelength multiplexing technology and multi-level modulation / demodulation technology that have been applied so far (Non-patent Document 1). As a technology to overcome this limitation, an optical communication technology using a multi-core fiber (MCF) as a transmission line is expected. A conventional fiber has only one core in one fiber. On the other hand, a multi-core fiber has a plurality of cores in one fiber, and is attracting attention as a transmission medium that enables high-capacity and high-density transmission. As a network to which a multi-core fiber is applied, researches assuming a short-haul system from a backbone system are actively performed in each organization (Non-patent Documents 1 and 2).

  In order to connect each signal transmitted through the multi-core fiber to the optical input / output unit of the apparatus, a connection component is required. According to the conventional method, a method of optically connecting light emitted from each core of a single multicore fiber to a plurality of single core fibers is disclosed (Patent Documents 1 and 2). In addition, as a method for connecting multi-core fibers, a method is disclosed in which light emitted from each core of one multi-core fiber is optically connected to each core of another multi-core fiber having the same arrangement (patent) Reference 3).

JP 2010-286697 A JP 2013-182222 A JP2013-105152A

Morioka et al. “Future innovative optical transport network technology”, NTT Technical Journal (2011.3) p. 32. Benjamin G. Lee, et. Al., “End-to-End Multicore Fiber Optic Link Operating up to 120 Gb / s”, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 30, NO. 6, P. 886, MARCH 15, 2012

  Among high-capacity, high-density wiring networks that use multi-core fibers, the core system has a small number of cores (for example, 2, 3, 4, 6, 7, 8, 12, etc.) in order to reduce crosstalk between cores. In a short distance system using a multi-core fiber, it is possible to use a multi-core fiber having a larger number of cores (for example, 7, 8, 12, 19, 37, etc.) in consideration of a reduction in the number of connection wires. Here, when connecting a backbone optical signal to a short-distance system, it is necessary to connect multi-core fibers having different numbers of cores and different arrangements.

  A case where a conventional technique is used to connect multi-core fibers having different numbers of cores and different arrays will be described with reference to FIG. First, using a fan-out device 102 that optically connects each core of the first multi-core fiber 100 to a plurality of single-core fibers 101, a signal transmitted to each core is separated into the plurality of single-core fibers 101. . A plurality of single core fibers 101 and a plurality of single core fibers 201, 211, 221,... Using a fan-in device 202 that optically connects the same number of single-core fibers 201 as the number of inputs of the second multi-core fiber 200 to the second multi-core fiber 200, the optical signal from each single-core fiber 201 is second Are transmitted to each core of the multi-core fiber 200. When the number of cores of the first multi-core fiber 100 is larger than the number of cores of the second multi-core fiber 200, the excess of the optical signal of the first multi-core fiber 100 is the third, fourth,. , 220,... Are optically connected using fan-in devices 212, 222,. On the other hand, when the number of cores of the first multicore fiber 100 is smaller than the number of cores of the second multicore fiber 200, the surplus cores of the second multicore fiber are added to the fifth, sixth,. The optical signal from the optical output can be optically connected using a fan-in / fan-out device.

  When the transmission capacity increases, the number of fan-in / fan-out devices and single-core fibers becomes enormous. Therefore, there arises a problem that it becomes difficult to accommodate the fiber and the fan-in / fan-out device in the apparatus, leading to an increase in cost and size of the apparatus. Also, even when the single core fiber is a linearly arranged ribbon fiber, the bending direction is limited, so that it is necessary to devise the fiber drawing, which makes it difficult to accommodate in the apparatus. Arise. Accordingly, it is desirable to provide an inexpensive and small-sized optical connection device compatible with a multi-fiber network even when the transmission capacity increases.

  In the present invention, a multicore fiber having a different number of cores and different arrangements is optically connected using a spatial optical system including lenses and prisms without branching a single multicore fiber into a plurality of conventional single core fibers. .

  One aspect of the present invention is a connection device that optically couples a multi-core fiber having a plurality of cores and a plurality of optical fibers including multi-core fibers having a different number of cores. Light emitted from a multi-core fiber having a plurality of cores passes through at least two lenses, and a group of light beams including at least one of the emitted light is converted into an optical path having the same traveling direction and different optical axes. The light passes through at least two lenses and enters a multi-core fiber having the same number of cores as the number of light beams included in the group.

  Since the light emitted from the fiber is diffused as it is, the optical path can be easily changed by passing the light through at least two lenses. In addition, by entering the multi-core fiber through at least two lenses, the input to each core of the fiber is facilitated.

  Another aspect of the present invention provides light from a first optical fiber having a first number of cores, a second optical fiber having a second number of cores different from the first number, And a third optical fiber having a third number of cores different from the number. In this apparatus, a first optical system that converts light transmitted from a first number of cores of a first optical fiber into a first number of parallel ray groups, and a first number of parallel ray groups. A conversion optical system that translates at least a part without changing the optical axis direction, and a second parallel light beam or a second light beam that is a part of the first number of parallel light beam groups that have passed through the conversion optical system. A second optical system that forms an image of the parallel light beam on the core of the second optical fiber, and a third parallel light that is the other part of the first number of parallel light beams that have passed through the conversion optical system. A third optical system that forms an image of the light beam or the third parallel light beam group on the core of the third optical fiber; By arranging a plurality of optical signals as parallel rays, the optical elements can be easily arranged.

  In a preferred example, at least one magnification of the first, second, and third optical systems is changed. By adding this configuration, it is possible to easily arrange the conversion optical system by changing the interval between the parallel rays. Alternatively, the light beam can be adapted to the diameters of the second and third fibers to be connected and can be coupled efficiently.

  In order to change the path of only a part of the plurality of light rays, a reflecting surface such as a prism is used, and at least a part of the parallel light ray group is caused to go straight without being translated. An example of forming a notch can be considered. The reflecting surface of the prism can be easily formed into a polygon such as a triangle or a quadrangle.

  In another preferable example, the second parallel light group is formed by the conversion optical system so that the optical axes of the respective light beams are arranged on the circumference when viewed from the optical axis direction, and the third parallel light group is In this way, the conversion optical system forms each light beam as it is arranged on the circumference when viewed from the optical axis direction. With this configuration, the optical signal is efficiently transmitted to the cores of the second and third optical fibers. Can be transmitted.

  Yet another aspect of the present invention is a multi-core fiber connection system in which optical fibers are connected using the above-described apparatus.

  According to the present invention, it is possible to easily optically connect multi-core fibers having different numbers of cores and different arrays.

Block diagram of configuration example of multi-core fiber optical connection with different number of cores and arrangement according to conventional technology Configuration diagram of multi-core fiber optic connection device of embodiment of the present invention Transmission diagram perpendicular to the optical axis of the optical path shift prism of the embodiment of the present invention Sectional drawing parallel to the optical axis of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention Sectional drawing parallel to the optical axis of the optical path shift prism of the Example of this invention Configuration diagram of multi-core fiber optic connection device of embodiment of the present invention Cross section of multi-core fiber Sectional drawing perpendicular | vertical to the optical axis of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention Configuration diagram of multi-core fiber optic connection device of embodiment of the present invention Cross section of multi-core fiber The perspective view from a perpendicular | vertical viewpoint to the optical axis of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention The perspective view of the optical path shift prism of the Example of this invention Sectional drawing parallel to the optical axis of the optical path shift mirror of the Example of this invention The block diagram seen from the viewpoint perpendicular | vertical to the optical axis of the optical path shift mirror of the Example of this invention The block diagram seen from the viewpoint perpendicular | vertical to the optical axis of the optical path shift mirror of the Example of this invention The perspective view of the prism holder of the Example of this invention The perspective view of the assembly method of the multi-core fiber optical connection apparatus of the Example of this invention The perspective view of the assembly method of the multi-core fiber optical connection apparatus of the Example of this invention Assembly perspective view of a multi-core fiber optical connecting device of an embodiment of the present invention

  Embodiments will be described in detail with reference to the drawings. However, the present invention is not construed as being limited to the description of the embodiments below. Those skilled in the art will readily understand that the specific configuration can be changed without departing from the spirit or the spirit of the present invention.

  In the structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and redundant description may be omitted.

  In the present specification and the like, notations such as “first”, “second”, and “third” are attached to identify the components, and do not necessarily limit the number or order. In addition, a number for identifying a component is used for each context, and a number used in one context does not necessarily indicate the same configuration in another context. Further, it does not preclude that a component identified by a certain number also functions as a component identified by another number.

  The position, size, shape, range, and the like of each component illustrated in the drawings and the like may not represent the actual position, size, shape, range, or the like in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings and the like. Any component expressed in the singular herein shall include the plural unless the context clearly dictates otherwise.

  A connection device using a spatial optical system including lenses and prisms is provided between multi-core fibers having different numbers of cores. The shape of the prism is determined so that light from some cores can be selectively transmitted or reflected. In particular, the method of selecting the core is devised so as to minimize the number of parts by efficiently using optical elements in consideration of symmetry.

  Differences from the prior art will be described. Patent Documents 1 and 2 disclose a technique for coupling light of a multicore fiber to a single core fiber or a plurality of single core fibers arranged in a straight line by using a lens or a prism. However, a specific example of connection to a multicore fiber in which a plurality of adjacent cores are two-dimensionally arranged in a single cladding layer is not described. Patent Document 3 discloses a technique for combining light of multi-core fibers having the same number of cores using a lens or a prism. Although it is described that an optical element may be inserted in the middle, an application example to multi-core fibers having different numbers of cores is not described. On the other hand, in the present invention, examples of how to select a core for efficiently connecting the light of a multicore fiber to a multicore fiber having a different number of cores, the shape of the prism, and the arrangement are shown. According to the present invention, the size of the connection device can be made substantially the same as in any of Patent Documents 1 to 3, and the size reduction can be maintained even if a function of connection to a multi-core fiber having a different number of cores is added. Since the input / output of the connection device according to the present invention is a multi-core fiber, the number of optical fibers to be used is reduced and space saving can be realized as compared with the conventional multi-core fiber input / single-core fiber output.

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

  Example 1 of an optical connecting device between multi-core fibers according to the present invention will be described with reference to FIGS. Hereinafter, the optical axis direction of the multi-core fiber is defined as the z axis, the direction perpendicular to the paper surface of FIG. 2 is defined as the x axis, and the vertical direction is defined as the y axis.

  FIG. 2 shows an optical connection between a multi-core fiber 100 having a core for passing 12 signals arranged on the circumference and multi-core fibers 200 and 300 having a core for passing 6 signals arranged on the circumference. The block diagram of the optical connection apparatus which performs is shown. As shown in FIG. 2, the multi-core fiber optical connection device 50 of the present invention includes a multi-core fiber 100, collimating lenses 51 and 52, an optical path shift prism group 60, lenses 53, 54, 55 and 56, and multi-core fibers 200 and 300. Composed. In general, a fiber having a larger number of cores is more susceptible to crosstalk, and is suitable for short-range communication. For example, the multi-core fiber 100 can be used for in-device or indoor wiring, and the multi-core fibers 200 and 300 can be used for long-distance communication.

  Light emitted from odd-numbered cores (indicated by black circles) among the cores 1 to 12 of the multicore fiber 100 passes through the two collimating lenses 51 and 52 and is point-symmetric with respect to the common focal point of each lens. By being guided to the position and suppressing the spread of the diameter, the light travels in parallel so as not to overlap the light from the adjacent cores, and passes through the optical path shift prism group 60. The light passes through the lenses 55 and 56, is guided to a point-symmetrical position with respect to the common focal point of each lens, suppresses the spread of the diameter, becomes parallel light, and enters each core of the multicore fiber 300. In general, since it is considered that the odd core interval extracted from the multi-core fiber 100 and the core interval of the multi-core fiber 300 are different, the focal lengths of the lenses 55 and 56 are changed to adjust the magnification. For example, when the distance between the centers of the core 1 and the core 7 of the multicore fiber 100 is 0.18 mm and the distance between the centers of two opposing cores of the multicore fiber 300 is 0.09 mm, the magnification is 0.5. Therefore, the focal length of the lens 56 is half of the focal length of the lens 55.

  Light emitted from even-numbered cores (indicated by white circles) among the cores 1 to 12 of the multicore fiber 100 passes through the two collimating lenses 51 and 52 and is point-symmetric with respect to the common focal point of each lens. By being guided to the position and suppressing the spread of the diameter, the light travels in parallel so as not to overlap with the light from the adjacent cores, and is reflected twice in the optical path shift prism group 60. The light passes through the lenses 53 and 54, is guided to a point-symmetrical position with respect to the common focal point of each lens, suppresses the spread of the diameter, becomes parallel light, and enters each core of the multicore fiber 200. In general, it is considered that the even core interval extracted from the multi-core fiber 100 is different from the core interval of the multi-core fiber 200, so the magnification is adjusted by changing the focal length of the lenses 53 and 54. For example, when the distance between the centers of the core 2 and the core 8 of the multicore fiber 100 is 0.18 mm and the distance between the centers of two opposing cores of the multicore fiber 200 is 0.09 mm, the magnification is 0.5. Therefore, the focal length of the lens 54 is half of the focal length of the lens 53. Here, the prism 62 inside the optical path shift prism group 60 will be described with reference to FIGS.

  FIG. 3 is a view of the optical path shift prism group 60 as viewed from the multi-core fiber 100 side. The optical axis from the odd-numbered core (indicated by a black circle) goes straight in the z-direction, and the optical axis from the even-numbered core (indicated by a white circle) is deflected in the y-direction by the slope of the prism. Yes.

  FIG. 4 is a cross-sectional view parallel to the optical axis of the optical path shift prism 62.

  The prism 62 at the center of the optical path shifting prism group 60 has a rectangular cross section perpendicular to the optical axis and a parallelogram shown in FIG. 4 parallel to the optical axis. It has the role of translating the optical axis of the optical signal by reflection at the surfaces 65 and 67.

As shown in FIG. 5, the three-dimensional image is, for example, a hexahedron. For example, when quartz glass is used as the material of the prism 62, the refractive index with respect to light having a wavelength of 1550 nm is 1.444, and the condition that the light is totally reflected at the interface with air (refractive index 1) is the incident critical angle 43. .83 degrees (sin ⁻¹ (1 / 1.444)) or more. The angle θ ₁ between the surface 64 and the surface 65 and the angle θ ₂ between the surface 66 and the surface 67 are about 45 ± 1 degrees so that the condition of total reflection of light is satisfied and the optical axis is easily controlled. Is desirable. In addition, the reflectance when the light having a wavelength of 1550 nm is vertically incident at the interface between the quartz glass and the air is 3.3%. Therefore, in order to transmit the light from the odd cores of the multicore fiber 100, the surface 64 and the surface It is desirable to apply an antireflection coating to 66 and to install the prism 62 in the multi-core fiber optical connection device 50 so as to have a surface perpendicular to the optical axis of the incident light. When the surface 64 and the surface 66 are not perpendicular to the optical axis of the incident light, the optical axis is shifted due to the refraction of light in the prism. However, since the surface 64 and the surface 66 are parallel to each other, the emitted light is light Translate while keeping the axis spacing. In order to prevent light scattering, the surface 64, the surface 65, the surface 66, and the surface 67 need to have a surface roughness that is as flat as the wavelength. When the wavelength is shorter, there is no problem because the critical angle is smaller than the above because the refractive index of quartz glass is larger than the above. When the wavelength is longer, the refractive index n is larger than that of quartz glass at that wavelength, the incident critical angle sin ⁻¹ (1 / n) is less than 45 degrees, and it is necessary to use a transparent material such as plastic.

  The prism 61 and the prism 63 at both ends of the optical path shift prism group 60 have the same basic structure as the prism 62 and have a role of translating the optical axes of the optical signals from the even cores of the multi-core fiber 100. However, as apparent from FIG. 3, the prism 61 and the prism 63 should not block the optical axes of the odd-numbered cores of the multicore fiber 100, particularly the cores 1 and 7. For this purpose, a hole for transmitting light is provided so that the total reflection surface of the prism does not cover the optical axis of the odd-numbered core.

  FIG. 6 shows a perspective view of a configuration example of an optical path shift prism provided with a configuration that does not block the optical axis.

  FIG. 7 is a perspective view of another configuration example of the optical path shift prism provided with a configuration that does not block the optical axis.

  As an example of the prism shape provided with the hole, the rectangular hole 68 as shown in FIG. 6 or the cylindrical hole 69 as shown in FIG. 7 may be used, and the processing accuracy of the surface of the hole does not matter.

  FIG. 8 is a perspective view of still another example of the optical path shift prism provided with a configuration that does not block the optical axis. As shown in the perspective view of FIG. 8A, the surface 66 is extended so that the two vertical surfaces of the prism come to the position of the optical axis 70 from the odd-numbered core indicated by the arrow without providing a hole in the prism. Also good. FIG. 8B is a cross-sectional view parallel to the optical axis 70 of the prism, and shows how light from odd-numbered cores can be transmitted through the surfaces 64 and 66 with antireflection coating.

  The multi-core fiber optical connection device 50 in FIG. 2 needs to be large enough to accommodate the optical fiber to be connected. As the outer diameters of the two multi-core fibers 200 and 300 on the emission side in FIG. 2, a minimum of 0.25 mm or 0.9 mm is often used. When these optical fibers are used, the prisms 61 to 63 as a whole have a size of about 10 to 20 mm in consideration of the position where the optical axis should be shifted. The thickness of the prisms 61 to 63 is, for example, 1 to several millimeters in order to facilitate handling. The focal lengths of the lenses 51 to 56 can be set in a range of, for example, 1 to several millimeters as being reduced in size within an easy range. As described above, the multi-core fiber optical connecting device 50 can be realized with a diameter of about 10 to 20 millimeters and a length of about several tens to 100 millimeters.

  In addition, when the 12 cores of the multi-core fiber 100 are arranged not on the circumference as shown in FIG. 2 but on the outer circumference of the hexagonal lattice, they can be connected with the same configuration. In addition, when the multi-core fiber 200 or 300 has one core at the center of the six cores shown in FIG. 2 and seven cores in a hexagonal lattice arrangement as a whole, the center core is not used. It becomes applicable by doing.

  This configuration can also be applied when the input / output directions are reversed, that is, when light is emitted from the multicore fibers 200 and 300 and enters the multicore fiber 100 in FIG.

  A second embodiment of the optical connecting device between multi-core fibers according to the present invention will be described with reference to FIGS.

  FIG. 9 shows a multi-core fiber 400 having a core for passing 37 signals arranged on a hexagonal lattice, and six multi-core fibers 500, 600 having a core for passing seven signals each arranged on a hexagonal lattice. The block diagram of the optical connection apparatus which optically connects with the single core fiber 700 is shown. As shown in FIG. 9, the multi-core fiber optical connection device 50 of the present invention includes a multi-core fiber 400, collimating lenses 51 and 52, an optical path shift prism group 60, lenses 53, 54, 55, and 56, multi-core fibers 500 and 600, and It is composed of a single core fiber 700. The four multi-core fibers other than the multi-core fibers 500 and 600 are not shown in FIG. 9 for ease of understanding. The prism group 60 also shows only 71 and 72 among the six prisms. In this configuration, a cross-sectional view of a portion rotated by 60 degrees and 120 degrees around the fiber 700 is the same as FIG. Of the multi-core fibers 500 and 600, the core X indicated by a light color is an unused core.

  FIG. 10 shows a cross section of the multi-core fiber 400. Hereinafter, each core of the multi-core fiber 400 is divided into the six regions 401 to 406 and the central core 1 shown in FIG.

  The light emitted from the core 1 of the multi-core fiber 400 passes through the two collimating lenses 51 and 52 and suppresses the spread of the diameter so that it does not overlap with the light from the adjacent cores, and proceeds in parallel. The light enters the core of the single core fiber 700. Light emitted from the cores 2 to 7 included in the region 401 of the multicore fiber 400 is guided to a point-symmetrical position with respect to a common focal point of each lens through the two collimating lenses 51 and 52, and adjacent to each other. The light travels in parallel so as not to overlap with the light from the core of the light beam and is reflected twice in the prism 72 in the optical path shift prism group 60. The light passes through the lenses 55 and 56, is guided to a point-symmetrical position with respect to the common focal point of each lens, suppresses the spread of the diameter, becomes parallel light, and enters each core of the multicore fiber 600. When the core interval of the multi-core fiber 400 and the core interval of the multi-core fiber 600 are different, the magnification is adjusted by changing the focal length of the lenses 55 and 56. For example, when the distance between the centers of adjacent cores of the multi-core fiber 400, for example, the center of the core 1 and the core 3 is 0.04 mm, and the distance between the centers of two adjacent cores of the multi-core fiber 600 is 0.05 mm Since the magnification needs to be 1.25, the focal length of the lens 54 is set to 1.25 times the focal length of the lens 53.

  Regions 402, 403, 404, 405, and 406 of the multi-core fiber 400 have the same shape as the region 401, and the regions 401 are rotated clockwise by 60, 120, 180, 240, and 300 degrees, respectively, with respect to the fiber center. It is in. Therefore, the same effect can be realized by rotating the optical system in the region 401 by each angle. For example, light emitted from a core included in the region 404 is guided to a point-symmetrical position with respect to a common focal point of each lens through two collimating lenses 51 and 52, and light from adjacent cores. In parallel, the light beam is reflected twice in the prism 71 (at a position where the prism 72 is rotated 180 degrees with respect to the fiber center) in the optical path shift prism group 60. Through the lenses 53 and 54 (positions where the lenses 55 and 56 are rotated by 180 degrees with respect to the fiber center), they are guided to a point-symmetrical position with respect to the common focal point of each lens, and the spread of the diameter is suppressed. Then, it becomes parallel light and enters each core of the multi-core fiber 500. When the core interval of the multi-core fiber 400 and the core interval of the multi-core fiber 500 are different, the magnification is adjusted by changing the focal length of the lenses 53 and 54.

  Here, the six prisms 71, 72,... In the optical path shift prism group 60 will be described with reference to FIGS.

FIG. 11 is a cross-sectional view of the optical path shift prism group 60 as viewed from the multi-core fiber 400 side. The prism 72 of the optical path shift prism group 60 has a polygon including a region 401 ′ in which light from the core whose cross section perpendicular to the optical axis is included in the region 401 of the multicore fiber 400 passes after passing through the collimating lenses 51 and 52. A pentagon), and a cross section parallel to the optical axis is a parallelogram shown in FIG. 9, and has a role of translating the optical axes of optical signals from the cores 2 to 7 of the multicore fiber 400. When the angles θ ₃ and θ ₄ of the six prisms 71, 72,... Shown in FIG. 11 are set to 120 degrees in total (error is + 0 / −1 degree), they are bonded and fixed to adjacent prisms. Cheap.

FIG. 12 shows a perspective view of the prism 71. The three-dimensional image is, for example, a heptahedron shown in FIG. The optical axis 73 of the light emitted from one of the cores of the multi-core fiber 400 is translated by reflection on the shaded surface of the prism 71. For example, when quartz glass is used as the material of the prisms 71, 72,..., The angles θ ₁ and θ ₂ in FIG. 12 are about 45 ° ± 1 ° for the same reason as described in the first embodiment. Is desirable. Similarly, it is better to apply an antireflection coating on the entrance surface and the exit surface of the prism.

  The multi-core fiber optical connection device 50 in FIG. 9 needs to be large enough to accommodate the optical fiber to be connected. The outer diameter including the coating of the six multi-core fibers 500, 600,..., And the single core fiber 700 on the output side in FIG. ing. When these optical fibers are used, the prisms 71 to 76 in FIG. 11 have a total size of about several tens of millimeters in consideration of the position where the optical axis should be shifted. The thickness of the prisms 71 to 76 is at least about three times the core interval of the multi-core fiber, but is set to, for example, 1 to several millimeters for easy handling. The focal lengths of the lenses 51 to 56 can be set in a range of, for example, 1 to several millimeters as being reduced in size within an easy range. As described above, the multi-core fiber optical connection device 50 can be realized with a diameter of about 10 to several tens of millimeters and a length of about several tens to hundreds of millimeters.

  This configuration is also applied when the input / output directions are reversed, that is, when light is emitted from the multi-core fibers 500, 600,... And the single-core fiber 700 in FIG. it can.

  A third embodiment of the optical connecting device between multi-core fibers according to the present invention will be described with reference to FIGS.

  FIG. 13 shows a multi-core fiber 800 having a core for passing 19 signals arranged on a hexagonal lattice and three multi-core fibers 500, 600 having a core for passing seven signals arranged on a hexagonal lattice. 1 is a configuration diagram of an optical connection device that optically connects 610 and a single core fiber 700. FIG. As shown in FIG. 13, the multi-core fiber optical connection device 50 of the present invention includes a multi-core fiber 800, collimating lenses 51 and 52, and an optical path shift prism group 60 including six prisms, and three sets of lenses 53, 54, and 55. , 56 (with another set of lenses for multicore fiber 610, but not shown in FIG. 13), multicore fibers 500, 600, 610, and single core fiber 700. The optical path shift prism group 60 has a total of six prisms arranged in two rows of three in the z direction, but only four of them (prisms 74 to 77) are shown in FIG.

  FIG. 14 shows a cross section of the multi-core fiber 800. Hereinafter, each core of the multi-core fiber 400 is divided into three regions 801, 802, 803 and the central core 1 shown in FIG.

  The light emitted from the core 1 of the multi-core fiber 800 passes through the two collimating lenses 51 and 52 and suppresses the spread of the diameter so that it does not overlap with the light from the adjacent cores. The light enters the core of the single core fiber 700. Light emitted from the cores 2 to 6 included in the region 801 of the multi-core fiber 800 is guided to a point-symmetrical position with respect to a common focal point of each lens through the two collimating lenses 51 and 52, and has a diameter of By suppressing the spread, the light travels in parallel so as not to overlap with light from adjacent cores and is reflected twice in the prism 74 in the optical path shift prism group 60. The light passes through the lenses 53 and 54, is guided to a point-symmetrical position with respect to the common focal point of each lens, suppresses the spread of the diameter, becomes parallel light, and enters each core of the multicore fiber 500. The light emitted from the core 7 included in the region 801 of the multi-core fiber 800 is guided to a point-symmetrical position with respect to a common focal point of each lens through the two collimating lenses 51 and 52, and spreads in diameter. By suppressing, the light travels in parallel so as not to overlap with light from adjacent cores, and is reflected three times within the prism 75 in the optical path shift prism group 60. The light passes through the lenses 53 and 54, is guided to a point-symmetrical position with respect to the common focal point of each lens, suppresses the spread of the diameter, becomes parallel light, and enters the corresponding core of the multicore fiber 500. When the core interval of the multi-core fiber 800 and the core interval of the multi-core fiber 500 are different, the magnification is adjusted by changing the focal length of the lenses 53 and 54. For example, when the distance between adjacent cores of the multi-core fiber 800, for example, the center between the core 1 and the core 2 is 0.04 mm, and the distance between the centers of two adjacent cores of the multi-core fiber 500 is 0.05 mm Since the magnification needs to be 1.25, the focal length of the lens 54 is set to 1.25 times the focal length of the lens 53.

  The regions 802 and 803 of the multi-core fiber 800 have the same shape as the region 801, and are located at positions obtained by rotating the region 801 clockwise by 120 and 240 degrees, respectively, with respect to the fiber center. Therefore, the same effect can be realized by rotating the optical system in the region 801 by each angle. For example, the light emitted from the core included in the region 802 passes through the two collimating lenses 51 and 52 and is guided to a point-symmetrical position with respect to the common focal point of each lens, thereby suppressing the spread of the diameter. In the optical path shift prism group 60, the prisms (the prisms 74 and 75 are rotated by 120 degrees with respect to the fiber center) in the optical path shift prism group 60 so as not to overlap with the light from the adjacent cores. Reflects twice or three times within 76, 77. Passing through the lenses 55 and 56 (positions where the lenses 53 and 54 are rotated 120 degrees with respect to the fiber center) are guided to a point-symmetrical position with respect to the common focal point of each lens, and the spread of the diameter is suppressed. Then, it becomes parallel light and enters each core of the multi-core fiber 600. When the core interval of the multi-core fiber 800 and the core interval of the multi-core fiber 600 are different, the magnification is adjusted by changing the focal length of the lenses 55 and 56.

  Here, the prisms 74, 75,... In the optical path shift prism group 60 will be described with reference to FIGS.

  FIG. 15 is a view of the optical path shift prism group 60 as viewed from the multi-core fiber 800 side. The regions 801, 802, and 803 of the multi-core fiber 800 move to the regions 801 ′, 802 ′, and 803 ′ after passing through the two collimating lenses 51 and 52, respectively. The prism 74 of the optical path shift prism group 60 is a polygon whose cross section perpendicular to the optical axis includes the optical axes from five cores in the region 801 ′ of the multicore fiber 800 (a pentagon in the figure), and a cross section parallel to the optical axis. Is a parallelogram shown in FIG. 13 and has a role of translating the optical axis of the optical signal from the cores 2 to 6 of the multi-core fiber 800.

  FIG. 16 is a perspective view of the prism 74. The three-dimensional image is, for example, a polyhedron shown in FIG.

FIG. 17 is an example of a perspective view of the prism 75 and has a role of translating the optical axis 78 of the optical signal from the core 7 of the multi-core fiber 800. Both the prisms 74 and 75 reflect light on the hatched surface to move the optical axis. Note that, for example, when quartz glass is used as the material of the prisms 74, 75,..., The angles θ ₁ and θ ₂ in FIG. 16 are 45 ° ± 1 for the same reason as described in the first embodiment. It is desirable to set the degree. If the angle θ _{5 in} FIG. 16 is set to 120 degrees (the error is + 0 / −1 degrees), it does not collide with an adjacent prism. Similarly, the angles θ ₁ , θ ₆ , and θ ₇ in FIG. 17 are preferably about 45 ° ± 1 °, and θ ₈ is preferably 90 °. Similarly, it is better to provide an antireflection coating on the entrance surface and the exit surface of the prism.

  The size of the multi-core fiber optical connection device 50 is about several tens of millimeters as in the second embodiment.

  This configuration can also be applied when the input / output directions are reversed, that is, when light is emitted from the multi-core fibers 500, 600, 610 and the single-core fiber 700 in FIG.

  Example 4 of the optical connecting device between multi-core fibers according to the present invention will be described with reference to FIGS. 9 and 18 to 20.

  In FIG. 9, an optical path shift mirror group 80 is used instead of the optical path shift prism group 60 in FIG.

  FIG. 18 shows a cross-sectional view parallel to the optical axis. In the figure, four mirrors 81, 82, 83, and 84 are shown, but in reality, twelve mirrors are arranged around the optical axis.

  FIG. 19 shows a view of the mirrors 81 and 82 located on the inner side in FIG. 18 as viewed from the direction perpendicular to the optical axis. This mirror deflects light traveling in the z direction in FIG. 18 toward the outer mirrors 83 and 84 on the xy plane.

  FIG. 20 shows a view of the mirrors 83 and 84 viewed from a direction perpendicular to the optical axis. This mirror deflects light from mirrors 81 and 82 in FIG. 18 in the z direction.

  The mirrors 82 and 84 of the optical path shift mirror group 80 are polygons including a region 401 ′ in which light from the core whose cross section perpendicular to the optical axis is included in the region 401 of the multicore fiber 400 passes through the collimating lenses 51 and 52 ( In FIG. 19, the mirror 82 has a hexagonal shape, and in FIG. 20, the mirror 84 has a trapezoidal shape. Further, the cross section parallel to the optical axis is a right isosceles triangle shown in FIG. 18, and has a role of translating the optical axes of the optical signals from the cores 2 to 7 of the multicore fiber 400. Similar to the prism of the second embodiment, it is easy to fix it by adhering to an adjacent mirror. The surface on which the mirror light is reflected is formed by depositing a metal or dielectric thin film by vapor deposition or sputtering, and the reflectance at the wavelength used is controlled to 99.5% or more. The movement of the optical axis is the same as that of the second embodiment outside the optical path shift mirror group 80, and the same effect can be obtained.

  The manufacturing process of the structure shown in FIG. 2 of the optical connection apparatus between multi-core fibers which is this invention is demonstrated using FIGS.

  The positions of optical components (optical fibers 100, 200, 300, lenses 51 to 56, prisms 61 to 63) are determined by optical design. Next, a main body that forms the outer shape of the multi-core fiber connection device 50 and a component holder that is perforated so as not to block the optical path are made of, for example, stainless steel.

  FIG. 21 is a perspective view of an example of the prism holder. The holders of the prisms 61 to 63 have holes through which an optical path passes, for example, 91 to 93 shown in FIG. The main body is divided at least in the vicinity of the prism mounting position.

  The optical components (lenses 51 to 56, prisms 61 to 63) are made of, for example, quartz (BK-7 or the like), and an antireflection coating is applied to each surface except the surface used for total reflection. After aligning each optical component, it is fixed to the corresponding holder by, for example, YAG welding or UV bonding. If necessary, for example, the optical component is sandwiched between a holder and a stainless steel holding plate and screwed.

  The fiber and lens assembly process will be described with reference to FIG. 85 to 87 are lens holders, 88 to 89 are multi-core fiber optical connection device bodies, 90 is a camera, and 91 to 93 are prism holders.

First, the lenses 51 and 52 and the multi-core fiber 100 are aligned and fixed to the holder 85. The lens 51 is fixed at a predetermined position of the holder 85, light having a wavelength used for all the cores of the multi-core fiber 100 is input, the multi-core fiber 100 is fixed by being separated by the focal length, and after passing through the lens 52, the parallel light The position of the lens 52 is determined while confirming with the camera 90 placed far away so as to be fixed to the holder 85. The holder 85 is fixed to the main body 89. The positional relationship of each component is as shown in FIG. At this time, the arrangement of the light emission points confirmed by the camera 90 is stored. Similarly, the lenses 53, 54, 55, and 56 and the multi-core fibers 200 and 300 are aligned, and fixed to the holders 86 and 87 at positions where the light emitting points are at the same predetermined intervals as described above.
The prism assembly process will be described with reference to FIG. As shown in FIG. 21, after the prism 63 is inserted into the holder 93, the holder 93 is fixed to the design position of the main body 88 shown in FIG. 23 by YAG welding. The prism 63 is fixed to the holder 93 by UV bonding after alignment. At the time of alignment, the holders 86 and 87 of the multi-core fibers 200 and 300 with lenses are temporarily fixed to the main body 88 while leaving a degree of freedom of rotation, and light of a wavelength used for each core is input. The light distribution in the distance after passing through the prism 63 is recorded by the camera 90, and the rotation of the holders 86 and 87 to which the multi-core fibers 200 and 300 are fixed and the prism 63 so as to coincide with the predetermined light position of the stored multi-core fiber 100. The prism 63 is fixed to the holder 93 by performing parallel alignment. Subsequently, the prisms 62 and 61 are similarly fixed to the holders 92 and 91 after alignment. The holders 86 and 87 to which the fibers 200 and 300 are fixed are fixed to the main body 88 by YAG welding.

  FIG. 24 is a perspective view showing an image when assembly is completed. Finally, as shown in FIG. 24, light is put into the fibers 200 and 300, the position of the main body 89 to which the fiber 100 is fixed is aligned, and fixed to the main body 88 by YAG welding.

  According to the above embodiment, it becomes possible to optically connect multi-core fibers having different numbers of cores and different arrangements. Even when the transmission capacity is increased, it is possible to suppress an increase in the number of ports of the optical device to which the optical fiber is connected and the number of wires of the single core fiber. In addition, a plurality of fan-in / fan-out devices are unnecessary, and the number of parts is reduced. Therefore, it is possible to provide an optical network compatible multi-core fiber connection device composed of inexpensive and small multi-core fibers.

  In particular, among large-capacity and high-density wiring networks that use multi-core fibers, the backbone system uses multi-core fibers with a small number of cores to reduce inter-core crosstalk, and the short-haul system reduces the number of connection wires. In consideration, it is possible to use a multi-core fiber having a larger number of cores. Here, when connecting a backbone optical signal to a short-distance system, it is necessary to connect multi-core fibers having different numbers of cores and different arrangements. By applying this embodiment described above, the number of cores and the arrangement of cores can be changed using a spatial optical system including lenses and prisms without branching a multicore fiber into a plurality of conventional single core fibers Different multi-core fibers can be optically connected to each other.

  The present invention is not limited to the embodiments described above, and includes various modifications. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

1 to 12 multi-core fiber core 50 multi-core fiber optical connecting device 51, 52 collimating lens 53-56 lens 60 optical path shift prism group 61-63 prism 64-67 prism face 68 rectangular hole 69 cylindrical hole 70 optical axes 71, 72 Prism 73 Optical axis 74 to 77 Prism 78 Optical axis 80 Optical path shift mirror group 81 to 84 Mirror 85 to 87 Lens holder 88 to 89 Multicore fiber optical connection device main body 90 Camera 91 to 93 Prism holder 100 Multicore fiber 101 Single core fiber 102 Fan-out device 103 Adapter 200, 210, 220 Multi-core fiber 201, 211, 221 Single-core fiber 202, 212, 222 Fan-out device 300, 400 Multi-core fiber 401-406 Multi-core fiber 400 500, 600 multicore fiber 700 single core fiber 800 indicating the position after the light in regions 401-406 passes through collimating lenses 51, 52, respectively, in the region 401′-406 ′ in the cross section of multicore fiber 400. Multi-core fibers 801 to 803 Regions 801 ′ to 803 ′ in the cross-section of the multi-core fiber 800. Regions in the cross-section of the multi-core fiber 800 indicate positions after the light in the regions 801 to 803 has passed through the collimating lenses 51 and 52, respectively.

Claims (15)

A connection device for optically coupling a multi-core fiber having a plurality of cores and a plurality of optical fibers including a multi-core fiber having a plurality of cores different from the above,
The light emitted from the multi-core fiber having a plurality of cores passes through at least two lenses,
A group of light beams including at least one of the emitted lights is included in the group through an optical component that is converted into an optical path having the same traveling direction and a different optical axis, through at least two lenses. Incident on a multi-core fiber with as many cores as the number of rays,
A multi-core fiber connection device characterized by that. A connection device for optically coupling a first multi-core fiber having a plurality of cores and a plurality of optical fibers including multi-core fibers having a plurality of cores different from the above,
The light emitted from the first multi-core fiber having the plurality of cores passes through at least two lenses,
The first light beam group that is a part of the emitted light is included in the group through an optical component that is converted into an optical path having the same traveling direction and a different optical axis, through at least two lenses. Incident on a second multi-core fiber having more cores than the number of rays
The second group of light rays that is another part of the emitted light passes through zero or at least two lenses without changing the optical axis, with or without the optical component. Incident on a third multi-core fiber having at least as many cores as the number of rays included in the group,
The multi-core fiber connection device according to claim 1, wherein: A connection device for optically coupling a first multi-core fiber having a plurality of cores and a plurality of optical fibers including multi-core fibers having a plurality of cores different from the above,
The light emitted from the first multi-core fiber having the plurality of cores passes through at least two lenses,
The first group of light rays that becomes a part of the emitted light passes through the first optical component that is converted into an optical path having the same traveling direction and different optical axis, through at least two lenses, Incident on a second multi-core fiber having at least as many cores as the number of rays in the group,
The second light beam group that is another part of the emitted light passes through a second optical component that is converted into another optical path having the same traveling direction and a different optical axis, and at least two lenses. Through a third multi-core fiber that has at least as many cores as the number of rays in the group,
The multi-core fiber connection device according to claim 1, wherein: A connection device for optically coupling a first multi-core fiber having a plurality of cores and a plurality of optical fibers including multi-core fibers having a plurality of cores different from the above,
The light emitted from the first multi-core fiber having the plurality of cores passes through at least two lenses,
The first group of light rays that becomes a part of the emitted light passes through the first optical component that is converted into an optical path having the same traveling direction and different optical axis, through at least two lenses, Incident on a second multi-core fiber having at least as many cores as the number of rays in the group,
The second light beam consisting of one of the emitted light is incident on a single core fiber through zero or at least two lenses without changing the optical axis.
The multi-core fiber connection device according to claim 1, wherein: A connection device for optically coupling a first multi-core fiber having a plurality of cores and a plurality of optical fibers including multi-core fibers having a plurality of cores different from the above,
The light emitted from the first multi-core fiber having the plurality of cores passes through at least two lenses,
The first group of light rays that becomes a part of the emitted light passes through the first optical component that is converted into an optical path having the same traveling direction and different optical axis, through at least two lenses, Incident on a second multi-core fiber having at least as many cores as the number of rays in the group,
The second light beam group that is another part of the emitted light passes through a second optical component that is converted into another optical path having the same traveling direction and a different optical axis, and at least two lenses. Through a third multi-core fiber with more cores than the number of rays in the group,
The third light beam consisting of one of the emitted light is incident on a single core fiber through zero or at least two lenses without changing the optical axis.
The multi-core fiber connection device according to claim 1, wherein:   2. The multi-core fiber connection device according to claim 1, wherein the optical component converted into an optical path having the same traveling direction and a different optical axis is a prism, and uses total reflection on the prism surface. Light from a first optical fiber having a first number of cores, a second optical fiber having a second number of cores different from the first number, and a third different from the first number A third optical fiber having a number of cores and a connecting device for transmitting to the third optical fiber,
A first optical system that converts light transmitted from the first number of cores of the first optical fiber into a first number of parallel light beam groups;
A conversion optical system that translates at least a part of the first number of parallel light beam groups without changing the optical axis direction;
A second parallel light beam or a second parallel light beam group that is a part of the first number of parallel light beam beams that have passed through the conversion optical system is imaged on the core of the second optical fiber. With the optical system
The third parallel light beam or the third parallel light beam, which is another part of the first number of parallel light beams that have passed through the conversion optical system, is imaged on the core of the third optical fiber. A third optical system;
A multi-core fiber connecting device. The conversion optical system is
A reflecting surface composed of a prism surface for deflecting at least a part of the parallel light beam group in a direction perpendicular to the optical axis;
The multi-core fiber connection device according to claim 7. The reflection surface has a polygonal projection as viewed from the optical axis direction, and has a notch for at least a part thereof to move straight without translating at least a part of the parallel ray group,
The multi-core fiber connection device according to claim 8. The second parallel light beam group is formed by the conversion optical system as each light beam is arranged on the circumference when viewed from the optical axis direction.
The third parallel light beam group is formed by the conversion optical system as each light beam is arranged on the circumference when viewed from the optical axis direction.
The multi-core fiber connection device according to claim 7. The second optical system or the third optical system is an optical system that converts magnification at the time of image formation.
The multi-core fiber connection device according to claim 7. The light from the center core of the first optical fiber is converted into the second parallel light beam or the third parallel light beam without being translated by the conversion optical system. Forming an image on an optical fiber or a third optical fiber;
The multi-core fiber connection device according to claim 7. A first optical fiber having a first number of cores;
A second optical fiber having a second number of cores different from the first number;
A third optical fiber having a third number of cores different from the first number;
A connection device for transmitting light from the first optical fiber to the second optical fiber and the third optical fiber;
The connecting device is
A first optical system that converts light transmitted from the first number of cores of the first optical fiber into a first number of parallel light beam groups;
A conversion optical system that translates at least a part of the first number of parallel light beam groups without changing the optical axis direction;
A second optical system that forms an image on the core of the second optical fiber of the second parallel light beam or the parallel light beam group that is a part of the first number of parallel light beam groups that have passed through the conversion optical system. When,
A third parallel light beam or a parallel light beam group that is the other part of the first number of parallel light beam beams that have passed through the conversion optical system is imaged on the core of the third optical fiber. Optical system,
A multi-core fiber connection system. The conversion optical system includes:
A reflection surface that reflects at least a part of the parallel light beam group in a direction perpendicular to the optical axis;
The multi-core fiber connection system according to claim 13. At least a part of the reflecting surface has a notch for causing at least a part of the parallel rays to go straight.
The multi-core fiber connection system according to claim 14.

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