Optical waveguide and optical wiring component

Abstract

The present invention provides an optical waveguide and an optical wiring component that can reduce the burden of connection work or the like and also contribute to the simplification of the structure of a device to be connected thereto. An optical waveguide according to the present invention has a core pattern. The core pattern is provided with a first incidence / emission surface, a second incidence / emission surface, a third incidence / emission surface, a fourth incidence / emission surface, a fifth incidence / emission surface, a sixth incidence / emission surface, a seventh incidence / emission surface, an eighth incidence / emission surface, a first branching part, a second branching part, a third branching part, a fourth branching part, a first intersection part, a second intersection part, and a third intersection part. The first incidence / emission surface, the second incidence / emission surface, the fifth incidence / emission surface, and the six incidence / emission surface are in line symmetry with the third incidence / emission surface, the fourth incidence / emission surface, the seventh incidence / emission surface, and the eighth incidence / emission surface with respect to a first straight line. The first incidence / emission surface, the second incidence / emission surface, the third incidence / emission surface, and the fourth incidence / emission surface are in line symmetry with the fifth incidence / emission surface, the six incidence / emission surface, the seventh incidence / emission surface, and the eighth incidence / emission surface with respect to a second straight line.

Description

Optical waveguides and optical wiring components

[0001] The present invention relates to an optical waveguide and an optical wiring component.

[0002] Patent Document 1 discloses a branched optical waveguide that divides an input optical signal or mixes two input optical signals into one. This branched optical waveguide has a first core portion and a second core portion and a third core portion that are branched from the first core portion, and is Y-shaped.

[0003] Patent Document 2 discloses an optical waveguide in which core portions merge and branch in an X-shape. This optical waveguide enables mixing of optical signals and distribution of the mixed optical signals.

[0004] Patent Document 3 discloses an optical waveguide device including two branching patterns each having an optical branching element that branches input light and two optical waveguides into which the branched input light is input, and a merging pattern that merges the input light input to one branching pattern with the input light input to the other branching pattern, and then branches and outputs the resulting light. With this optical waveguide device, after each of the two input lights is branched, the branched input lights can be mixed together and then branched and output again.

[0005] These optical waveguides enable distribution and mixing of optical signals without converting them into electrical signals, which allows for faster and more energy-efficient distribution and mixing of large volumes of data.

[0006] Furthermore, Patent Document 1 discloses a technology for multiplexing light of different wavelengths, and Patent Document 2 discloses a technology for transmitting optical signals in both upstream and downstream directions through a single optical waveguide by changing the wavelength of the optical signal.

[0007] JP 2017-151275 A International Publication No. 2021 / 192674 International Publication No. 2012 / 086846

[0008] In the branched optical waveguide described in Patent Document 1, the core portion has a Y-shaped linear shape. Therefore, the structure has a directional property, and great care must be taken during the connection work. Furthermore, in the optical waveguide device described in Patent Document 3, the optical branching element and the optical coupler have different functions, so the propagation direction of light is limited to one direction. However, because these optical waveguides are layered, it may be difficult to determine the direction from the outside. Therefore, there is a concern that the input and output sides of the optical waveguide may be reversed during the connection work of these optical waveguides to optical fibers.

[0009] Furthermore, in the optical waveguide described in Patent Document 2, the core portion has an X-shaped line shape. Therefore, if the structure is designed isotropically, the directionality can be ignored. However, Patent Document 2 does not take such a configuration into consideration.

[0010] Furthermore, when transmitting both upstream and downstream optical signals through a single optical waveguide using light of different wavelengths, the equipment connected to the optical waveguide must handle light of different wavelengths, which can lead to a complex structure of the equipment.

[0011] An object of the present invention is to provide an optical waveguide and an optical wiring component that can reduce the burden of connection work and contribute to simplifying the structure of the equipment to be connected.

[0012] These objects can be achieved by the present invention described below in (1) to (13). (1) An optical waveguide having a sheet-like core pattern extending along a plane and propagating light, the core pattern comprising: a first input / output surface, a second input / output surface, a third input / output surface, and a fourth input / output surface provided at one end of the core pattern; a fifth input / output surface, a sixth input / output surface, a seventh input / output surface, and an eighth input / output surface provided at the other end of the core pattern; a first transmission section connected to the first input / output surface; a second transmission section connected to the second input / output surface; a third transmission section connected to the third input / output surface; a fourth transmission section connected to the fourth input / output surface; a fifth transmission section connected to the fifth input / output surface; a sixth transmission section connected to the sixth input / output surface; a seventh transmission section connected to the seventh input / output surface; and an eighth transmission section connected to the eighth input / output surface; a first branch section branching the second transmission section; a second branch section branching the fourth transmission section; a third branch section that branches the sixth transmission section, and a fourth branch section that branches the eighth transmission section, a first intersection section that connects the first transmission section to the third branch section and connects the first branch section to the fifth transmission section, a second intersection section that connects the first branch section to the fourth branch section and connects the second branch section to the third branch section, and a third intersection section that connects the second branch section to the seventh transmission section and connects the third transmission section to the fourth branch section, wherein when two straight lines that are orthogonal to each other in the plane are defined as a first straight line and a second straight line, a relationship of line symmetry is established between the first input / output surface, the second input / output surface, the fifth input / output surface, and the sixth input / output surface, and the third input / output surface, the fourth input / output surface, the seventh input / output surface, and the eighth input / output surface, with the first straight line as an axis of symmetry, an optical waveguide characterized in that a relationship of line symmetry exists between the first input / output surface, the second input / output surface, the third input / output surface, and the fourth input / output surface and the fifth input / output surface, the sixth input / output surface, the seventh input / output surface, and the eighth input / output surface, with the second straight line as an axis of symmetry.

[0013] (2) An optical waveguide according to (1) above, wherein a relationship of line symmetry with respect to the first straight line is established between the linear shape of the first branch portion and the linear shape of the second branch portion, and between the linear shape of the third branch portion and the linear shape of the fourth branch portion, respectively; and a relationship of line symmetry with respect to the second straight line is established between the linear shape of the first branch portion and the linear shape of the third branch portion, and between the linear shape of the second branch portion and the linear shape of the fourth branch portion, respectively.

[0014] (3) The optical waveguide according to (1) or (2) above, wherein the intersection angle of the first intersection portion, the intersection angle of the second intersection portion, and the intersection angle of the third intersection portion are 15° or more and 45° or less.

[0015] (4) The optical waveguide according to any one of (1) to (3) above, wherein the first intersection, the second intersection, and the third intersection have low refractive index portions across which incident light crosses.

[0016] (5) The optical waveguide according to (4), wherein the thickness of the low refractive index portion in the direction in which the light is incident is 1.0 μm or more and 4.0 μm or less.

[0017] (6) The optical waveguide according to any one of (1) to (5) above, wherein the width of each of the second incident / exit surface, the fourth incident / exit surface, the sixth incident / exit surface, and the eighth incident / exit surface is 20 μm or more and 55 μm or less.

[0018] (7) The optical waveguide according to (6), wherein the core pattern includes a curved portion, and the curved portion has a bending radius of 5 mm or more and 15 mm or less.

[0019] (8) The optical waveguide according to (7) above, wherein the curved portion has a shape that follows a clothoid curve.

[0020] (9) An optical waveguide according to any one of (1) to (8) above, including a laminate comprising: a core layer including the core pattern; a first clad layer laminated on one surface of the core layer; and a second clad layer laminated on the other surface of the core layer.

[0021] (10) The optical waveguide according to (9), wherein the laminate is dimensionally symmetrical about a plane that is parallel to the plane and passes through the middle of the thickness of the core layer.

[0022] (11) The optical waveguide according to (9) or (10) above, wherein the laminate is entirely made of a resin material.

[0023] (12) An optical wiring component comprising: the optical waveguide according to any one of (1) to (11) above; a first optical fiber connected to the second incident / exit surface; a second optical fiber connected to the fourth incident / exit surface; a third optical fiber connected to the fifth incident / exit surface; a fourth optical fiber connected to the sixth incident / exit surface; a fifth optical fiber connected to the eighth incident / exit surface; and a sixth optical fiber connected to the seventh incident / exit surface.

[0024] (13) The optical wiring component according to (12) above, comprising: a first light-emitting unit that causes light to be incident on the core pattern via the first optical fiber; a first light-receiving unit that receives light emitted from the core pattern via the second optical fiber; a second light-receiving unit that receives light emitted from the core pattern via the third optical fiber; a second light-emitting unit that causes light to be incident on the core pattern via the fourth optical fiber; a third light-receiving unit that receives light emitted from the core pattern via the fifth optical fiber; and a third light-emitting unit that causes light to be incident on the core pattern via the sixth optical fiber.

[0025] According to the present invention, an optical waveguide and an optical wiring component can be obtained that can reduce the burden of connection work and contribute to simplifying the structure of the equipment to be connected.

[0026] Fig. 1 is a schematic diagram showing an optical wiring component according to an embodiment. Fig. 2 is a plan view showing an optical waveguide according to an embodiment. Fig. 3 is an enlarged view of a first intersection shown in Fig. 1. Fig. 4 is an enlarged perspective view showing a portion of the optical waveguide of Fig. 1. Fig. 5 is a perspective view showing an example of an optical waveguide with a ferrule. Fig. 6 is a partially exploded perspective view showing an optical wiring component including the optical waveguide with a ferrule, a housing, a first connecting portion and a second connecting portion of Fig. 5, and a fiber ribbon.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical waveguide and optical wiring component of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0028] 1. Optical Wiring Component First, an optical waveguide and an optical wiring component according to an embodiment will be described.

[0029] Fig. 1 is a schematic diagram showing an optical wiring component 10 according to an embodiment of the present invention. Fig. 2 is a plan view showing an optical waveguide 1 according to an embodiment of the present invention.

[0030] In each drawing of the present application, three mutually orthogonal axes are set as an X-axis, a Y-axis, and a Z-axis, which are indicated by arrows. The tip end of the arrow is referred to as the "plus side," and the base end is referred to as the "minus side." The plus side of the Z-axis is also referred to as the "upper side," and the minus side of the Z-axis is also referred to as the "lower side."

[0031] The optical wiring component 10 shown in FIG. 1 includes an optical waveguide 1, a first optical fiber F1, a second optical fiber F2, a third optical fiber F3, a fourth optical fiber F4, a fifth optical fiber F5, and a sixth optical fiber F6.

[0032] The optical waveguide 1 has a core pattern CP that propagates light. This core pattern CP connects the end face on the negative Y-axis side with the end face on the positive Y-axis side. The core pattern CP distributes and mixes the incident optical signals.

[0033] The optical waveguide 1 is disposed between the first optical fiber F1 and the second optical fiber F2 and the third optical fiber F3, the fourth optical fiber F4, the fifth optical fiber F5 and the sixth optical fiber F6, optically connecting them to relay optical signals.

[0034] The optical wiring component 10 shown in FIG. 1 includes a first light-emitting portion T1, a first light-receiving portion R1, a second light-emitting portion T2, a second light-receiving portion R2, a third light-emitting portion T3, and a third light-receiving portion R3.

[0035] The first light-emitting unit T1 and the first light-receiving unit R1 are electrically connected to the first electronic device E1 shown in Fig. 1. The second light-emitting unit T2 and the second light-receiving unit R2 are electrically connected to the second electronic device E2 shown in Fig. 1. The third light-emitting unit T3 and the third light-receiving unit R3 are electrically connected to the third electronic device E3 shown in Fig. 1.

[0036] The first light-emitting unit T1 emits light to the core pattern CP via the first optical fiber F1, the second light-emitting unit T2 emits light to the core pattern CP via the fourth optical fiber F4, and the third light-emitting unit T3 emits light to the core pattern CP via the sixth optical fiber F6.

[0037] The first light receiving unit R1 receives light emitted from the core pattern CP via the second optical fiber F2, the second light receiving unit R2 receives light emitted from the core pattern CP via the third optical fiber F3, and the third light receiving unit R3 receives light emitted from the core pattern CP via the fifth optical fiber F5.

[0038] 2. Optical Waveguide The optical waveguide 1 has a core pattern CP. An optical signal emitted from the first light-emitting unit T1 is split into two by the core pattern CP. The split optical signals are received by the second light-receiving unit R2 and the third light-receiving unit R3. The optical signals emitted from the second light-emitting unit T2 and the third light-emitting unit T3 are mixed by the core pattern CP. The mixed optical signal is received by the first light-receiving unit R1. This enables optical communication between the first electronic device E1 and the second electronic device E2, and between the first electronic device E1 and the third electronic device E3.

[0039] 2.1. Overview of Core Pattern The optical waveguide 1 shown in Figure 2 is in the form of a sheet that extends along a plane parallel to the X-Y plane. Two lines that intersect at right angles within this plane are designated as a first line L1 and a second line L2. The first line L1 is parallel to the Y axis, and the second line L2 is parallel to the X axis. The core pattern CP is composed of a core portion (optical transmission portion) that transmits optical signals. This core portion extends along the Y axis and is shaped to branch and merge along the way so as to distribute and mix the optical signals.

[0040] The core pattern CP includes a first incident / exit surface P1, a second incident / exit surface P2, a third incident / exit surface P3, a fourth incident / exit surface P4, a fifth incident / exit surface P5, a sixth incident / exit surface P6, a seventh incident / exit surface P7, and an eighth incident / exit surface P8. These incident / exit surfaces allow optical signals to enter the core pattern CP and allow optical signals to exit the core pattern CP.

[0041] The core pattern CP also includes a first transmission section C1 connected to the first incident / exit surface P1, a second transmission section C2 connected to the second incident / exit surface P2, a third transmission section C3 connected to the third incident / exit surface P3, a fourth transmission section C4 connected to the fourth incident / exit surface P4, a fifth transmission section C5 connected to the fifth incident / exit surface P5, a sixth transmission section C6 connected to the sixth incident / exit surface P6, a seventh transmission section C7 connected to the seventh incident / exit surface P7, and an eighth transmission section C8 connected to the eighth incident / exit surface P8. These transmission sections extend along the Y axis.

[0042] Furthermore, the core pattern CP has a first branch portion B1 that branches the second transmission portion C2, a second branch portion B2 that branches the fourth transmission portion C4, a third branch portion B3 that branches the sixth transmission portion C6, and a fourth branch portion B4 that branches the eighth transmission portion C8.

[0043] The first branch B1 is shaped to branch the second transmission section C2 so that the separation distance in the X-axis direction increases as the branch progresses toward the positive side of the Y-axis. The second branch B2 is shaped to branch the fourth transmission section C4 so that the separation distance in the X-axis direction increases as the branch progresses toward the positive side of the Y-axis. The third branch B3 is shaped to branch the sixth transmission section C6 so that the separation distance in the X-axis direction increases as the branch progresses toward the negative side of the Y-axis. The fourth branch B4 is shaped to branch the eighth transmission section C8 so that the separation distance in the X-axis direction increases as the branch progresses toward the negative side of the Y-axis.

[0044] The core pattern CP also includes a first intersection X1, a second intersection X2, and a third intersection X3.

[0045] The first intersection X1 connects the first transmission section C1 and the third branch B3, and also connects the first branch B1 and the fifth transmission section C5. The second intersection X2 connects the first branch B1 and the fourth branch B4, and also connects the second branch B2 and the third branch B3. The third intersection X3 connects the second branch B2 and the seventh transmission section C7, and also connects the third transmission section C3 and the fourth branch B4. These intersections are shaped such that the cores cross each other in an X-shape within the same plane.

[0046] Such a core pattern CP establishes optical communication between the first electronic device E1 and the second electronic device E2 and the third electronic device E3 while distinguishing between downstream and upstream optical signals. In this specification, communication by an optical signal from the first electronic device E1 to the second electronic device E2 or the third electronic device E3 is referred to as "upstream communication," and communication by an optical signal from the second electronic device E2 or the third electronic device E3 to the first electronic device E1 is referred to as "downstream communication."

[0047] For example, if a core pattern with only one Y-shaped branch is used for both upstream and downstream communications, it is necessary to use light of different wavelengths. Therefore, devices that transmit and receive information via optical waveguides require special equipment, such as equipment used for wavelength division multiplexing (WDM) optical communications, to share the same line for both downstream and upstream communications. The need for such equipment has led to complex structures and high costs for devices that transmit and receive information.

[0048] In addition, when an optical element such as an optical isolator is used to separate downstream optical signals from upstream optical signals, a decrease in transmission quality also becomes an issue. Furthermore, depending on the structure, material, manufacturing method, etc. of the optical waveguide 1, the transmission quality may differ depending on the wavelength.

[0049] In contrast, the optical waveguide 1 shown in Figure 2 uses a core pattern CP with multiple branching sections and multiple intersections, allowing the line to be divided into sections for each transmission direction of the optical signal. This eliminates the need for devices used in wavelength division multiplexing optical communications, simplifying the structures of the light emitting section and the light receiving section. Furthermore, since optical elements for separating downstream and upstream optical signals are no longer required, degradation of transmission quality can be suppressed. Furthermore, by using light of the same wavelength for the downstream and upstream optical signals, the problem of different transmission quality depending on the wavelength can be resolved.

[0050] The core pattern CP described above also has the function of distributing and mixing optical signals. In the example of FIG. 1 , the optical signal S1 emitted from the first light-emitting unit T1 is incident on the second input / output surface P2 of the core pattern CP via the first optical fiber F1. The optical signal S1 is transmitted to the first branching unit B1 via the second transmission unit C2 and distributed into two optical signals, optical signals S1a and S1b. The optical signal S1a is emitted from the fifth input / output surface P5 via the first intersection X1 and the fifth transmission unit C5. It is then received by the second light-receiving unit R2 via the third optical fiber F3. The optical signal S1b is emitted from the eighth input / output surface P8 via the second intersection X2 and the eighth transmission unit C8. It is then received by the third light-receiving unit R3 via the fifth optical fiber F5. Such optical communication by transmitting the optical signals S1, S1a, and S1b is an example of the above-mentioned "upstream communication."

[0051] Meanwhile, the optical signal S2 emitted from the second light-emitting unit T2 is incident on the sixth input / output surface P6 of the core pattern CP via the fourth optical fiber F4. The optical signal S2 is transmitted to the third branching unit B3 via the sixth transmission unit C6 and split into two optical signals, optical signals S2a and S2b. The optical signal S2a is emitted from the first input / output surface P1 via the first intersection X1 and the first transmission unit C1. In the example of FIG. 1, the emitted optical signal S2a is not used for communication, so it can be forcibly attenuated or radiated into space. The optical signal S2b is transmitted to the second branching unit B2 via the second intersection X2.

[0052] The optical signal S3 emitted from the third light-emitting unit T3 is incident on the seventh incident / exit surface P7 of the core pattern CP via the sixth optical fiber F6, and is transmitted to the second branching unit B2 via the third intersection X3.

[0053] The optical signals S2b and S3 are mixed in the second branching section B2. The mixed optical signals S2b and S3 are output from the fourth input / output surface P4 via the fourth transmission section C4. They are then received by the first light receiving section R1 via the second optical fiber F2. Such optical communication using the transmission of the optical signals S2, S2b, and S3 is an example of the "downstream communication" mentioned above.

[0054] 1, information output by the first electronic device E1 can be distributed to the second electronic device E2 and the third electronic device E3 via the core pattern CP. Such optical communication technology is suitable for use in, for example, a passive optical network (PON). The passive optical network may also be an in-vehicle network.

[0055] The first electronic device E1 is not particularly limited, but for example, when the first electronic device E1 is an in-vehicle device, examples of the first electronic device E1 include various sensors such as an image sensor like a camera, a ranging sensor like a LiDAR (Laser Imaging, Detection and Ranging) or a millimeter wave sensor, and an antenna module. In the following description, the first electronic device E1 may be referred to as a "slave function unit." The slave function unit often generates a large amount of information in a short period of time. For this reason, a large communication capacity is required for upstream communication.

[0056] The second electronic device E2 and the third electronic device E3 each include a computing device such as a microcomputer. Specifically, if the second electronic device E2 and the third electronic device E3 are in-vehicle devices, examples of such devices include an ECU (Electronic Control Unit), a navigation device, a TCU (Telematics Communication Unit), and a gateway device. In the following description, the second electronic device E2 and the third electronic device E3 may each be referred to as a "master function unit." The master function unit performs calculations on large amounts of information and realizes various functions based on the calculation results. In many cases, real-time processing of information in the master function unit is required, so high communication speeds are required for upstream communication.

[0057] The above-described core pattern CP enables high-speed, high-capacity upstream communication. Therefore, optical communication using the optical waveguide 1 allows the master function unit to process large amounts of information in real time. This improves real-time communication while simplifying and reducing the cost of each light-emitting unit and each light-receiving unit. Furthermore, because the above-described information distribution can be performed using optical signals, master function units can be parallelized while reducing power consumption, contributing to, for example, system redundancy and multi-functionality. Furthermore, the core pattern CP has the function of distributing information output from the first electronic device E1 to the second electronic device E2 and the third electronic device E3, which is useful in that it eliminates the need for multiple first light-emitting units T1.

[0058] On the other hand, the above-described core pattern CP enables high-speed, high-capacity communication even in downstream communication. Note that, in downstream communication, optical signals output from multiple master functional units may be mixed. For example, in FIG. 1, when optical signal S2 and optical signal S3 are output simultaneously, optical signal S2b and optical signal S3 are mixed in the second branching unit B2. In this case, a technique may be used to prevent collision between information contained in optical signal S2b and information contained in optical signal S3. Examples of such a technique include time division multiple access (TDMA) and time division multiplexing (TDM). Furthermore, wavelength division multiplexing (WDM) may be used as long as the costs required for demultiplexing, multiplexing, etc. are within an acceptable range.

[0059] 1, the second input / output surface P2 is the input surface for the optical signal S1, and the fifth input / output surface P5 and the eighth input / output surface P8 are the output surfaces for the optical signals S1a and S1b. Furthermore, the sixth input / output surface P6 and the seventh input / output surface P7 are input surfaces, and the fourth input / output surface P4 is the output surface. Therefore, the output surfaces and the input surfaces are alternately arranged along the X axis at the end surface on the positive side of the Y axis of the optical waveguide 1.

[0060] To establish both upstream and downstream communications between the first electronic device E1 and the second electronic device E2, and between the first electronic device E1 and the third electronic device E3, it is necessary to route a third optical fiber F3 and a fourth optical fiber F4 between the optical waveguide 1 and the second electronic device E2, and a fifth optical fiber F5 and a sixth optical fiber F6 between the optical waveguide 1 and the third electronic device E3. Since the exit and entrance surfaces are alternately arranged at the end face of the optical waveguide 1, the optical fibers can be routed without crossing each other. This eliminates the load associated with crossing optical fibers, prevents a decrease in reliability, and reduces the difficulty of the wiring work.

[0061] On the other hand, if the two exit surfaces and two entrance surfaces at the end face of the optical waveguide 1 are separated by a first straight line L1, the optical fibers will need to cross each other, which may result in a decrease in reliability and make wiring work more difficult.

[0062] 2, the first input / output surface P1, the second input / output surface P2, the fifth input / output surface P5, and the sixth input / output surface P6 are symmetrical with the third input / output surface P3, the fourth input / output surface P4, the seventh input / output surface P7, and the eighth input / output surface P8, with the first straight line L1 as the axis of symmetry. Specifically, this symmetrical relationship means that the widths and positions of the corresponding input / output surfaces are symmetrical with each other. In other words, assuming that the optical waveguide 1 is folded along the first straight line L1, the widths and positions of the first incident / exit surface P1 and the third incident / exit surface P3, the second incident / exit surface P2 and the fourth incident / exit surface P4, the fifth incident / exit surface P5 and the seventh incident / exit surface P7, and the sixth incident / exit surface P6 and the eighth incident / exit surface P8 are the same. Note that the width of the incident / exit surface refers to the width of the incident / exit surface in the X-axis direction.

[0063] When this relationship is satisfied, the width and position of each incident / exit surface of the optical waveguide 1 do not change even when the optical waveguide 1 is rotated (flipped) 180 degrees around the first straight line L1 as a rotation axis. In other words, the width and position of each incident / exit surface are equivalent before and after the flip. Therefore, when the optical waveguide 1 is used to connect to an optical fiber, there is no need to worry about the flip around the first straight line L1 as a rotation axis. Therefore, the optical waveguide 1 contributes to reducing the burden of the connection work. In addition, the optical waveguide 1 may be housed in a housing or the like (not shown) and used as an optical connecting component. Even in the assembly work of such optical connecting components, there is no need to worry about the flip around the first straight line L1 as a rotation axis, so the burden of the assembly work can be reduced.

[0064] 2, the first input / output surface P1, the second input / output surface P2, the third input / output surface P3, and the fourth input / output surface P4 are symmetrical with the fifth input / output surface P5, the sixth input / output surface P6, the seventh input / output surface P7, and the eighth input / output surface P8, with the second line L2 being the axis of symmetry. In other words, assuming that the optical waveguide 1 is folded along the second line L2, the widths and positions of the first input / output surface P1 and the fifth input / output surface P5, the second input / output surface P2 and the sixth input / output surface P6, the third input / output surface P3 and the seventh input / output surface P7, and the fourth input / output surface P4 and the eighth input / output surface P8 are the same.

[0065] When this relationship is established, even if the optical waveguide 1 is rotated (flipped) 180 degrees around the second straight line L2 as the rotation axis, the width and position of each input / output surface remain unchanged. In other words, the width and position of each input / output surface are equivalent before and after the flip. Therefore, when the optical waveguide 1 is used in the connection work with an optical fiber, there is no need to worry about the flipping around the second straight line L2 as the rotation axis. Therefore, the optical waveguide 1 contributes to reducing the burden of the connection work. Furthermore, when the optical waveguide 1 is used in the assembly work of optical connecting components, there is no need to worry about the flipping around the second straight line L2 as the rotation axis, which reduces the burden of the assembly work.

[0066] The term "the widths are the same" means that the difference in width between two corresponding entrance and exit surfaces is 20% or less of the average width of the two entrance and exit surfaces. Specifically, when the average width of the two corresponding entrance and exit surfaces is 50 μm, the difference in width may be 10 μm or less.

[0067] Furthermore, the term "aligned positions" means that, when the optical waveguide 1 is assumed to be folded along the first straight line L1 or the second straight line L2, the deviation between the midpoints of the widths of the two corresponding incident and exit surfaces is 20% or less of the average width of the two incident and exit surfaces. Specifically, when the average width of the two corresponding incident and exit surfaces is 50 μm, the deviation may be 10 μm or less.

[0068] 2.3 Shape of Core Pattern Next, the shape of the core pattern CP will be described.

[0069] As shown in Figure 2, the width of the first entrance / exit surface P1 is WP1, the width of the second entrance / exit surface P2 is WP2, the width of the third entrance / exit surface P3 is WP3, the width of the fourth entrance / exit surface P4 is WP4, the width of the fifth entrance / exit surface P5 is WP5, the width of the sixth entrance / exit surface P6 is WP6, the width of the seventh entrance / exit surface P7 is WP7, and the width of the eighth entrance / exit surface P8 is WP8.

[0070] In this case, it is preferable that the optical waveguide 1 satisfies the relationships expressed by the following formulas (1) to (4).

[0071] 1.8 x WP1 ≤ WP2 ≤ 2.2 x WP1 ... (1) 1.8 x WP3 ≤ WP4 ≤ 2.2 x WP3 ... (2) 1.8 x WP5 ≤ WP6 ≤ 2.2 x WP5 ... (3) 1.8 x WP7 ≤ WP8 ≤ 2.2 x WP7 ... (4)

[0072] When the optical waveguide 1 satisfies the above formulas (1) to (4), it is possible to suppress losses associated with the distribution and mixing of optical signals at each branching section. Therefore, if the width of each input / output surface does not satisfy the above formulas (1) to (4), there is a risk that losses associated with the distribution and mixing of optical signals will increase.

[0073] Each of the widths WP2, WP4, WP6, and WP8 is preferably about 5 μm or more and 100 μm or less, more preferably about 10 μm or more and 70 μm or less, and even more preferably about 20 μm or more and 55 μm or less, thereby achieving good dimensional accuracy and low transmission loss, excellent connectivity with optical fibers, and a compact optical waveguide 1.

[0074] If the widths WP2, WP4, WP6, and WP8 are below the lower limit values, there is a risk that the incidence efficiency will decrease when an optical signal is incident from an optical fiber to the optical waveguide 1, for example. Furthermore, it may become more difficult to form the core pattern CP, which may result in a decrease in dimensional accuracy and an increase in transmission loss. On the other hand, if the widths WP2, WP4, WP6, and WP8 exceed the upper limit values, there is a risk that the incidence efficiency will decrease when an optical signal is emitted from the optical waveguide 1 to an optical fiber, for example. Furthermore, there is a risk that the optical waveguide 1 will become larger.

[0075] The center-to-center distance between the first incident / exit surface P1 and the second incident / exit surface P2, the center-to-center distance between the third incident / exit surface P3 and the fourth incident / exit surface P4, the center-to-center distance between the fifth incident / exit surface P5 and the sixth incident / exit surface P6, and the center-to-center distance between the seventh incident / exit surface P7 and the eighth incident / exit surface P8 are each referred to as a pitch PT. The pitch PT is preferably set to approximately 200 to 3000 μm, more preferably approximately 400 to 2000 μm, and even more preferably approximately 600 to 1000 μm. This makes it possible to improve connectivity to optical fibers while avoiding the optical waveguide 1 from being too wide in the X-axis direction.

[0076] If the pitch PT is below the lower limit, the connectivity may be reduced depending on the diameter of the optical fiber. On the other hand, if the pitch PT is above the upper limit, the width of the optical waveguide 1 may become too wide. In this case, the bending radius of the curved portion CL included in the core pattern CP may become small, which may increase bending loss. To avoid this, it may be necessary to increase the overall length of the optical waveguide 1.

[0077] The total length TL of the optical waveguide 1 in the Y-axis direction varies depending on the pitch PT, etc., but is preferably 3 mm to 30 mm, more preferably 5 mm to 20 mm, and even more preferably 7 mm to 14 mm. This makes it possible to suppress bending loss in the curved portion CL included in the core pattern CP, while achieving a sufficient miniaturization of the optical waveguide 1.

[0078] The lengths of the first transmission section C1, the second transmission section C2, the third transmission section C3, the fourth transmission section C4, the fifth transmission section C5, the sixth transmission section C6, the seventh transmission section C7, and the eighth transmission section C8 are each referred to as the transmission section length LC. The transmission section length LC is preferably 0.3 mm or more and 2.0 mm or less, and more preferably 0.5 mm or more and 1.5 mm or less. This reduces coupling loss between each input / output surface and the optical fiber while minimizing adverse effects associated with excessively long transmission section lengths LC. Examples of such adverse effects include a small bending radius at the curved section CL of each branch section, which increases bending loss, and an excessively long total length TL.

[0079] Furthermore, it is preferable that there is a linear symmetry relationship between the linear shape of the first branch portion B1 and the linear shape of the second branch portion B2, and between the linear shape of the third branch portion B3 and the linear shape of the fourth branch portion B4, with the first straight line L1 as the axis of symmetry.

[0080] When this relationship is established, even if the optical waveguide 1 is rotated (flipped) by 180 degrees around the first straight line L1 as the rotation axis, the linear shape of each branching section remains unchanged. In other words, there is no difference in bending loss at each branching section before and after the flipping. Therefore, when such an optical waveguide 1 is used for connection to an optical fiber or assembly work, there is no need to worry about flipping around the first straight line L1 as the rotation axis. Therefore, the optical waveguide 1 contributes to reducing the burden of connection work and assembly work.

[0081] The relationship of line symmetry with the first straight line L1 as the axis of symmetry mentioned above means that, assuming that the optical waveguide 1 is folded at the first straight line L1, the linear shape of the first branch portion B1 overlaps with the linear shape of the second branch portion B2, and the linear shape of the third branch portion B3 overlaps with the linear shape of the fourth branch portion B4.

[0082] Furthermore, it is preferable that there is a linear symmetry relationship between the linear shape of the first branch portion B1 and the linear shape of the third branch portion B3, and between the linear shape of the second branch portion B2 and the linear shape of the fourth branch portion B4, with the second straight line L2 as the axis of symmetry.

[0083] When this relationship is established, even if the optical waveguide 1 is rotated (flipped) by 180 degrees around the second straight line L2 as the rotation axis, the linear shape of each branching section remains unchanged. In other words, there is no difference in bending loss at each branching section before and after the flipping. Therefore, when such an optical waveguide 1 is used for connection to an optical fiber or assembly work, there is no need to worry about flipping around the second straight line L2 as the rotation axis. Therefore, the optical waveguide 1 contributes to reducing the burden of connection work and assembly work.

[0084] The relationship of line symmetry with the second straight line L2 as the axis of symmetry mentioned above means that, when it is assumed that the optical waveguide 1 is folded at the second straight line L2, the linear shape of the first branch portion B1 overlaps with the linear shape of the third branch portion B3, and the linear shape of the second branch portion B2 overlaps with the linear shape of the fourth branch portion B4.

[0085] The overlapping of the linear shapes means that the core portions constituting each branch portion overlap with each other, but also includes a state in which there is some misalignment. Specifically, it is sufficient if the amount of misalignment between the center lines of the core portions is 20% or less of the minimum width of the core portions.

[0086] The branching ratios of the first branch portion B1, the second branch portion B2, the third branch portion B3, and the fourth branch portion B4 are preferably 40:60 to 60:40, and more preferably 45:55 to 55:45. This allows the branching characteristics to be substantially equivalent before and after the inversion, even when the optical fiber is inverted around the first straight line L1 or the second straight line L2.

[0087] The core pattern CP shown in Fig. 2 includes a curved portion CL. As shown in Fig. 2, the curved portion CL is included in, for example, the first branch portion B1. The same applies to the other branch portions. In the curved portion CL, the core portion is gradually bent, so that a branch structure can be realized while suppressing bending loss.

[0088] The bending radius of the curved portion CL included in each branch portion is defined as r. When the central axis of the curved portion CL is approximated by an arc, the bending radius r is the minimum radius of the arc. The bending radius r is not particularly limited, but is preferably set to 5 mm or more and 15 mm or less. This makes it possible to suppress bending loss while preventing the total length TL from becoming too long.

[0089] If the bending radius r is below the lower limit, the bending loss may increase, whereas if the bending radius r is above the upper limit, the total length TL may become too long.

[0090] Furthermore, it is preferable that the curved portion CL has a shape that follows a clothoid curve. A clothoid curve is a curve in which the reciprocal of the bending radius (curvature) increases in proportion to the length of the curved portion CL. By having the curved portion CL have a shape that follows a clothoid curve, bending loss can be easily suppressed even when the bending radius r is reduced.

[0091] The intersection angle of the first intersection point X1 shown in FIG. 2 is denoted by θ. The intersection angle θ is not particularly limited, but is preferably 15° or more and 45° or less, and more preferably 20° or more and 35° or less. If the intersection angle θ is within the above range, the intersection loss at each intersection point can be suppressed and the total length TL can be prevented from becoming too long. Furthermore, it is also possible to prevent the bending radius r from becoming small in the curved portion CL included in each branch point. The above range of the intersection angle θ preferably also applies to the intersection angle of the second intersection point X2 and the intersection angle of the third intersection point X3.

[0092] If the intersection angle θ is below the lower limit, the intersection loss may increase. The intersection loss refers to, for example, the loss caused by the optical signal S1a shown in FIG. 1 leaking into the first transmission section C1 or the third branch section B3. Furthermore, the total length TL of the optical waveguide 1 may become long due to the relationship with the pitch PT. On the other hand, if the intersection angle θ exceeds the upper limit, the bending radius r of the curved section CL may become small, which may increase the bending loss.

[0093] 3 is an enlarged view of the first intersection X1 shown in FIG. 1. The first intersection X1 shown in FIG. 3 has a low-refractive-index portion LR that crosses the incident light. At the first intersection X1 shown in FIG. 3, the first branch B1 and the fifth transmission portion C5 are connected at the middle portion M. Similarly, the third branch B3 and the first transmission portion C1 are connected at the middle portion M. Therefore, the middle portion M is configured to allow both the optical signal S1a and the optical signal S2a to pass through. The low-refractive-index portion LR is arranged to surround the middle portion M.

[0094] With this configuration, when the optical signal S1a that has entered the intermediate portion M attempts to leak out to the third branch portion B3 or the first transmission portion C1, the optical signal S1a is reflected by the low refractive index portion LR that is arranged between the intermediate portion M and the third branch portion B3 and the low refractive index portion LR that is arranged between the intermediate portion M and the first transmission portion C1. Similarly, when the optical signal S2a that has entered the intermediate portion M attempts to leak out to the first branch portion B1 or the fifth transmission portion C5, the optical signal S2a is reflected by the low refractive index portion LR that is arranged between the intermediate portion M and the first branch portion B1 and the low refractive index portion LR that is arranged between the intermediate portion M and the fifth transmission portion C5. This makes it possible to suppress crossing loss.

[0095] The refractive index of the low refractive index portion LR is set appropriately depending on the refractive index difference with the core portion, the propagation mode of the optical signals S1a and S2a, etc. Specifically, it is sufficient that the refractive index of the low refractive index portion LR is set so that the optical signal to be reflected by the low refractive index portion LR satisfies the condition of total reflection.

[0096] On the other hand, for example, the low refractive index portion LR disposed between the first branch portion B1 and the intermediate portion M, and the low refractive index portion LR disposed between the intermediate portion M and the fifth transmission portion C5 transmit the optical signal S1a. At this time, the angle of incidence of the optical signal S1a with respect to the low refractive index portion LR is sufficiently small, so that transmission loss can be suppressed. The same is true for the optical signal S2a.

[0097] The thickness t of the low refractive index portion LR in the incident direction of light is not particularly limited, but is preferably 1.0 μm or more and 10.0 μm or less, and more preferably 1.0 μm or more and 4.0 μm or less, which can suppress the transmission loss of the low refractive index portion LR and increase the reflection efficiency of light that should be reflected by the low refractive index portion LR.

[0098] It is also preferable that the low refractive index portion LR is provided at the second intersection X2 and the third intersection X3, so that the crossing loss in the entire optical waveguide 1 can be suppressed.

[0099] 1 to 3 have been described above, but the core pattern CP may be expanded, for example, toward the negative side of the X axis. "Expansion" refers to increasing the number of input and output surfaces, and therefore the number of transmission sections, branch sections, and intersection sections. This allows the number of slave function sections and master function sections connected to the core pattern CP to be increased.

[0100] When expanding the core pattern CP, core portions having the same shape as the pattern unit U shown in FIG. 2 may be linked in equal numbers to both the positive and negative sides of the X axis of the core pattern CP shown in FIG.

[0101] 2.4. Laminated Structure FIG. 4 is an enlarged perspective view of a portion of the optical waveguide 1 of FIG.

[0102] As described above, the optical waveguide 1 shown in Fig. 4 is in the form of a sheet extending along a plane parallel to the XY plane. The optical waveguide 1 shown in Fig. 4 includes a laminate 16 formed by laminating, from the bottom, a first support layer 18, a first clad layer 11, a core layer 13, a second clad layer 12, and a second support layer 19 in this order.

[0103] As shown in Fig. 4, the core portion 14 formed in the core layer 13 has its side surfaces surrounded by the side cladding portions 15, the first cladding layer 11, and the second cladding layer 12. The refractive index of the core portion 14 is higher than the refractive index of these cladding regions. This allows light to be confined and propagated in the core portion 14. A core pattern CP is formed by such core portions 14. Note that Fig. 4 corresponds to an enlarged view of a portion where two core portions 14 are arranged side by side, such as the first transmission portion C1 and the second transmission portion C2 shown in Fig. 1.

[0104] The laminate 16 has a laminated structure, which facilitates the production of the optical waveguide 1. Furthermore, the core layer 13 is sandwiched between the first cladding layer 11 and the second cladding layer 12, which stabilizes the refractive index difference at the interface. This makes it possible to form the core layer 13 including the core portion 14 with low transmission loss.

[0105] The laminated structure is not essential. For example, at least a portion of the side cladding portion 15 may be integrated with at least one of the first cladding layer 11 and the second cladding layer 12.

[0106] In the core layer 13, the refractive index distribution within the cross section of the core portion 14 may be any distribution, for example, a so-called step index (SI) type distribution in which the refractive index changes discontinuously, or a so-called graded index (GI) type distribution in which the refractive index changes continuously.

[0107] The cross-sectional shape of the core portion 14 in the X-Z plane, i.e., the transverse cross-sectional shape of the core portion 14, is not particularly limited, but examples thereof include circles such as perfect circles, ellipses, and ovals, polygons such as triangles, rectangles, pentagons, and hexagons, and other irregular shapes.

[0108] The average thickness of the core layer 13 is not particularly limited, but is preferably about 1 to 200 μm, more preferably about 5 to 100 μm, and even more preferably about 10 to 70 μm, which ensures the optical properties and mechanical strength required for the core layer 13.

[0109] The constituent material of the core layer 13 is not particularly limited, but examples thereof include resin materials, glass materials, silicon materials, composite materials of these with other materials, etc. Among these, resin materials are preferably used from the viewpoints of impact resistance, ease of handling, etc.

[0110] The average thickness of each of the first cladding layer 11 and the second cladding layer 12 is preferably about 1 to 200 μm, more preferably about 3 to 100 μm, and even more preferably about 5 to 60 μm, so that the optical properties and mechanical strength required for the first cladding layer 11 and the second cladding layer 12 are ensured.

[0111] The materials for the first cladding layer 11 and the second cladding layer 12 are appropriately selected from the materials listed above as the materials for the core layer 13 .

[0112] At least one of the first cladding layer 11 and the second cladding layer 12 may be provided as needed, and may be omitted.

[0113] The first support layer 18 is provided on the lower surface of the first clad layer 11. The second support layer 19 is provided on the upper surface of the second clad layer 12. By providing such first support layer 18 and second support layer 19, the core layer 13, the first clad layer 11, and the second clad layer 12 are protected from heat, external forces, and the like.

[0114] The constituent materials of the first support layer 18 and the second support layer 19 are not particularly limited, but examples thereof include resin materials, glass materials, silicon materials, composite materials of these with other materials, etc. Among these, resin materials are preferably used from the viewpoints of impact resistance, ease of handling, etc.

[0115] At least one of the first support layer 18 and the second support layer 19 may be provided as needed, and may be omitted.

[0116] 4, a plane F is imagined as being parallel to the XY plane and passing through the middle of the thickness of the core layer 13. The laminate 16 is preferably dimensionally symmetrical about this plane F. "Symmetry about plane F" means that the thickness distributions of the first cladding layer 11 and the second cladding layer 12 are the same across plane F. Also, preferably, the thickness distributions of the first support layer 18 and the second support layer 19 are the same across plane F.

[0117] Because the laminate 16 has this relationship, in the optical waveguide 1 formed by the laminate 16, even if the optical waveguide 1 is rotated 180 degrees around the first straight line L1 or the second straight line L2 as the rotation axis, the position of the input / output surface in the thickness direction of the optical waveguide 1 does not change. Therefore, when such an optical waveguide 1 is used for connection work with an optical fiber or assembly work, there is no need to worry about inversion around the first straight line L1 or the second straight line L2 as the rotation axis. Therefore, such an optical waveguide 1 contributes to reducing the burden of connection work and assembly work.

[0118] Furthermore, it is preferable that the entire laminate 16 be made of a resin material, which makes it possible to obtain an optical waveguide 1 that is excellent in impact resistance and ease of handling.

[0119] 3. Ferrule-equipped Optical Waveguide The optical waveguide 1 may be used with a ferrule attached to one or both ends, i.e., in the form of a ferrule-equipped optical waveguide. The ferrule-equipped optical waveguide may also be in a form in which the entire optical waveguide 1 is housed in a single ferrule.

[0120] Fig. 5 is a perspective view showing an example of a ferrule-equipped optical waveguide 2. The ferrule-equipped optical waveguide 2 shown in Fig. 5 includes an optical waveguide 1 and ferrules 24 and 26. The ferrules 24 and 26 may be, for example, PMT ferrules.

[0121] 4. Housing and Connection Portion The ferrule-equipped optical waveguide 2 may be used in a state where it is housed in a housing.

[0122] FIG. 6 is a partially exploded perspective view of the ferrule-equipped optical waveguide 2, the housing 3, the optical wiring component 20 including the first connecting portion 83 and the second connecting portion 93, and the fiber ribbons 81 and 91 shown in FIG.

[0123] 6 includes optical waveguide containers 31 and 32. These are combined to form a space for accommodating the optical waveguide 2 with a ferrule therein.

[0124] The fiber ribbon 81 shown in Fig. 6 is a component in which a first optical fiber F1 and a second optical fiber F2 are bundled together in a single ribbon shape. The fiber ribbon 91 shown in Fig. 6 is a component in which a third optical fiber F3, a fourth optical fiber F4, a fifth optical fiber F5, and a sixth optical fiber F6 are bundled together in a single ribbon shape. Ferrules 82, 92 are attached to the fiber ribbons 81, 91. Note that the fiber ribbons 81, 91 are not limited to ribbon-shaped components and may be other components, such as multi-core optical fiber cables.

[0125] 6 shows a first connection part 83 which is an assembly of two parts 830, 830, and a second connection part 93 which is an assembly of two parts 930, 930. The first connection part 83 connects one end of the ferrule-equipped optical waveguide 2 to a fiber ribbon 81 having a ferrule 82 attached thereto. The second connection part 93 connects the other end of the ferrule-equipped optical waveguide 2 to a fiber ribbon 91 having a ferrule 92 attached thereto.

[0126] 6 is configured from the above-described ferrule-equipped optical waveguide 2, housing 3, first connecting portion 83, second connecting portion 93, and fiber ribbons 81, 91 to which ferrules 82, 92 are attached. In such an optical wiring component 20, the optical waveguide 1 has a high degree of freedom in its orientation during the assembly work of accommodating the optical waveguide 1 in the housing 3 and during the connection work of connecting the assembled components to optical fibers, thereby reducing the burden on the worker.

[0127] 5. Advantages of the Present Embodiment As described above, the optical waveguide 1 according to this embodiment is an optical waveguide having a sheet shape that spreads along a plane and a core pattern CP that propagates light.

[0128] The core pattern CP includes a first incident / exit surface P1, a second incident / exit surface P2, a third incident / exit surface P3, a fourth incident / exit surface P4, a fifth incident / exit surface P5, a sixth incident / exit surface P6, a seventh incident / exit surface P7, and an eighth incident / exit surface P8, a first transmission section C1 connected to the first incident / exit surface P1, a second transmission section C2 connected to the second incident / exit surface P2, a third transmission section C3 connected to the third incident / exit surface P3, a fourth transmission section C4 connected to the fourth incident / exit surface P4, a fifth transmission section C5 connected to the fifth incident / exit surface P5, a sixth transmission section C6 connected to the sixth incident / exit surface P6, a seventh transmission section C7 connected to the seventh incident / exit surface P7, and an eighth transmission section C8 connected to the eighth incident / exit surface P8, The power supply cable includes a first branch B1 that branches the second transmission section C2, a second branch B2 that branches the fourth transmission section C4, a third branch B3 that branches the sixth transmission section C6, and a fourth branch B4 that branches the eighth transmission section C8, a first intersection X1 that connects the first transmission section C1 and the third branch B3 and connects the first branch B1 and the fifth transmission section C5, a second intersection X2 that connects the first branch B1 and the fourth branch B4 and connects the second branch B2 and the third branch B3, and a third intersection X3 that connects the second branch B2 and the seventh transmission section C7 and connects the third transmission section C3 and the fourth branch B4.

[0129] When two straight lines that are perpendicular to each other within a plane are defined as the first straight line L1 and the second straight line L2, a relationship of line symmetry exists between the first entrance / exit surface P1, the second entrance / exit surface P2, the fifth entrance / exit surface P5, and the sixth entrance / exit surface P6 and the third entrance / exit surface P3, the fourth entrance / exit surface P4, the seventh entrance / exit surface P7, and the eighth entrance / exit surface P8, with the first straight line L1 as the axis of symmetry.

[0130] Furthermore, a relationship of line symmetry exists between the first entrance / exit surface P1, the second entrance / exit surface P2, the third entrance / exit surface P3, and the fourth entrance / exit surface P4 and the fifth entrance / exit surface P5, the sixth entrance / exit surface P6, the seventh entrance / exit surface P7, and the eighth entrance / exit surface P8, with the second straight line L2 as the axis of symmetry.

[0131] With this configuration, the line can be divided according to the transmission direction of the optical signal, eliminating the need for devices used in wavelength division multiplexing optical communications and simplifying the structures of the light emitter and light receiver. Furthermore, since optical elements for separating downstream and upstream optical signals are no longer necessary, degradation of transmission quality can be suppressed. Furthermore, by using light of the same wavelength for the downstream and upstream optical signals, the problem of different transmission quality depending on the wavelength can be resolved.

[0132] Furthermore, since the optical waveguide 1 can distribute information as an optical signal, it is possible to reduce power consumption while, for example, parallelizing processing units for processing the distributed information, which can contribute to system redundancy and multi-functionality.

[0133] Furthermore, even if the optical waveguide 1 is rotated (flipped) by 180 degrees around the first straight line L1 or the second straight line L2 as the rotation axis, the width and position of each input / output surface remain unchanged. Therefore, when the optical waveguide 1 is used for connecting to an optical fiber, there is no need to worry about the flipping around the first straight line L1 or the second straight line L2 as the rotation axis. Therefore, the optical waveguide 1 can reduce the burden on the worker when used for connecting or assembling work.

[0134] Furthermore, in the optical waveguide 1 according to the above embodiment, a linear symmetry relationship exists between the linear shape of the first branch portion B1 and the linear shape of the second branch portion B2, and between the linear shape of the third branch portion B3 and the linear shape of the fourth branch portion B4, with the first straight line L1 as the axis of symmetry.

[0135] Furthermore, there is a relationship of line symmetry between the linear shape of the first branch portion B1 and the linear shape of the third branch portion B3, and between the linear shape of the second branch portion B2 and the linear shape of the fourth branch portion B4, with the second straight line L2 as the axis of symmetry.

[0136] With this configuration, even if the optical waveguide 1 is rotated (flipped) 180 degrees around the first straight line L1 or the second straight line L2 as the rotation axis, the linear shape of each branching section remains unchanged. When such an optical waveguide 1 is used for connection to an optical fiber, there is no need to worry about the inversion around the first straight line L1 or the second straight line L2 as the rotation axis. Therefore, the optical waveguide 1 can reduce the burden on the worker when used for connection or assembly work.

[0137] In the optical waveguide 1 according to the embodiment, the crossing angle of the first crossing point X1, the crossing angle of the second crossing point X2, and the crossing angle of the third crossing point X3 are 15° or more and 45° or less.

[0138] This configuration can suppress crossing loss at each crossing point and prevent the total length TL of the optical waveguide 1 from becoming too long. It can also prevent the bending radius from becoming small at the curved portion CL included in each branch point.

[0139] In the optical waveguide 1 according to the embodiment, the first intersection X1, the second intersection X2, and the third intersection X3 each have a low refractive index portion LR across which incident light crosses.

[0140] With this configuration, crossing loss at each crossing point can be reduced.

[0141] In the optical waveguide 1 according to the embodiment, the thickness t of the low refractive index portion LR in the direction in which light is incident is 1.0 μm or more and 4.0 μm or less.

[0142] According to this configuration, it is possible to suppress the transmission loss of the low refractive index portion LR and increase the reflection efficiency of the light that should be reflected by the low refractive index portion LR.

[0143] In addition, in the optical waveguide 1 according to the embodiment, the widths WP2, WP4, WP6, and WP8 of the second input / output surface P2, the fourth input / output surface P4, the sixth input / output surface P6, and the eighth input / output surface P8 are 20 μm or more and 55 μm or less.

[0144] With this configuration, it is possible to obtain an optical waveguide 1 that has good dimensional accuracy and small transmission loss, is excellent in connectivity with optical fibers, and is miniaturized.

[0145] In the optical waveguide 1 according to the embodiment, the core pattern CP includes a curved portion CL. The bending radius r of this curved portion CL is 5 mm or more and 15 mm or less.

[0146] With this configuration, it is possible to suppress the bending loss at the curved portion CL and prevent the total length TL from becoming too long.

[0147] In the optical waveguide 1 according to the embodiment, the curved portion CL has a shape that follows a clothoid curve.

[0148] With this configuration, even if the bending radius of the curved portion CL is made small, bending loss can be easily suppressed.

[0149] Furthermore, the optical waveguide 1 according to the embodiment includes a laminate 16 having a core layer 13 including a core pattern CP, a first clad layer 11 laminated on one side of the core layer 13, and a second clad layer 12 laminated on the other side of the core layer 13.

[0150] With this configuration, the laminate 16 has a laminated structure, which facilitates the manufacture of the optical waveguide 1. Furthermore, since the core layer 13 is sandwiched between the first cladding layer 11 and the second cladding layer 12, the refractive index difference at the interface is stabilized. This makes it possible to form the core layer 13 including the core portion 14 with low transmission loss.

[0151] In the optical waveguide 1 according to the embodiment, the laminate 16 is dimensionally symmetrical with respect to a plane F that is parallel to the plane and passes through the middle of the thickness of the core layer 13 .

[0152] With this configuration, even if the optical waveguide 1 is rotated 180 degrees around the first straight line L1 or the second straight line L2 as the rotation axis, the position of the input / output surface in the thickness direction of the optical waveguide 1 does not change. Therefore, when such an optical waveguide 1 is used for connection work with an optical fiber or assembly work, there is no need to worry about inversion around the first straight line L1 or the second straight line L2 as the rotation axis. Therefore, such an optical waveguide 1 can reduce the burden on the worker during connection work or assembly work.

[0153] In the optical waveguide 1 according to the embodiment, the laminate 16 is entirely made of a resin material.

[0154] With this configuration, an optical waveguide 1 having excellent impact resistance and ease of handling can be obtained.

[0155] Furthermore, the optical wiring component 10 according to the embodiment includes the optical waveguide 1 according to the embodiment, a first optical fiber F1 connected to the second input / output surface P2, a second optical fiber F2 connected to the fourth input / output surface P4, a third optical fiber F3 connected to the fifth input / output surface P5, a fourth optical fiber F4 connected to the sixth input / output surface P6, a fifth optical fiber F5 connected to the eighth input / output surface P8, and a sixth optical fiber F6 connected to the seventh input / output surface P7.

[0156] This configuration realizes the optical wiring component 10, which can reduce the burden on the worker, since assembly work can be performed without having to worry about the posture of the optical waveguide 1. Furthermore, when distributing the distributed optical signals to the two master function units, the optical fibers can be routed without crossing each other.

[0157] Moreover, the optical wiring component 10 according to the embodiment includes a first light-emitting unit T1 that causes light to be incident on the core pattern CP via the first optical fiber F1, a first light-receiving unit R1 that receives light emitted from the core pattern CP via the second optical fiber F2, a second light-receiving unit R2 that receives light emitted from the core pattern CP via the third optical fiber F3, a second light-emitting unit T2 that causes light to be incident on the core pattern CP via the fourth optical fiber F4, a third light-receiving unit R3 that receives light emitted from the core pattern CP via the fifth optical fiber F5, and a third light-emitting unit T3 that causes light to be incident on the core pattern CP via the sixth optical fiber F6.

[0158] With this configuration, upstream communication (communication by inputting light from the first optical fiber F1 to the core pattern CP and receiving the light emitted from the core pattern CP by the third optical fiber F3 and the fifth optical fiber F5) can be performed at all times without using technology to prevent collision of optical signals in each light-emitting unit or each light-receiving unit. This improves the real-time nature of communication while simplifying and reducing the cost of each light-emitting unit and each light-receiving unit.

[0159] While the optical waveguide and optical wiring component of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto. For example, the optical waveguide and optical wiring component of the present invention may have any configuration in which the components of the above-described embodiments are replaced with any configuration having the same function, or any component may be added to the above-described embodiments.

[0160] According to the present invention, an optical waveguide and an optical wiring component can be obtained that can reduce the burden of connection work, etc., and can contribute to simplifying the structure of the equipment to be connected. Therefore, the present invention has industrial applicability.

[0161] REFERENCE SIGNS LIST 1 Optical waveguide 2 Optical waveguide with ferrule 3 Housing 10 Optical wiring component 11 First cladding layer 12 Second cladding layer 13 Core layer 14 Core portion 15 Side cladding portion 16 Laminate 18 First support layer 19 Second support layer 20 Optical wiring component 24 Ferrule 26 Ferrule 31 Optical waveguide accommodating body 32 Optical waveguide accommodating body 81 Fiber ribbon 82 Ferrule 83 First connecting portion 91 Fiber ribbon 92 Ferrule 93 Second connecting portion 830 Component 930 Component B1 First branching portion B2 Second branching portion B3 Third branching portion B4 Fourth branching portion C1 First transmission portion C2 Second transmission portion C3 Third transmission portion C4 Fourth transmission portion C5 Fifth transmission portion C6 Sixth transmission portion C7 Seventh transmission section C8 Eighth transmission section CL Curved portion CP Core pattern E1 First electronic device E2 Second electronic device E3 Third electronic device F Surface F1 First optical fiber F2 Second optical fiber F3 Third optical fiber F4 Fourth optical fiber F5 Fifth optical fiber F6 Sixth optical fiber L1 First straight line L2 Second straight line LC Transmission section length LR Low refractive index section M Middle section P1 First incident / exit surface P2 Second incident / exit surface P3 Third incident / exit surface P4 Fourth incident / exit surface P5 Fifth incident / exit surface P6 Sixth incident / exit surface P7 Seventh incident / exit surface P8 Eighth incident / exit surface PT Pitch R1 First light-receiving section R2 Second light-receiving section R3 Third light-receiving section S1 Optical signal S1a Optical signal S1b Optical signal S2 Optical signal S2a Optical signal S2b Optical signal S3 Optical signal T1 First light-emitting part T2 Second light-emitting part T3 Third light-emitting part TL Total length U Pattern unit WP1 Width WP2 Width WP3 Width WP4 Width WP5 Width WP6 WidthWP7 Width WP8 Width X1 First intersection X2 Second intersection X3 Third intersection r Bending radius t Thickness θ Intersection angle

Claims

1. An optical waveguide having a sheet-like core pattern that spreads along a plane and propagates light, the core pattern comprising: a first input / output surface, a second input / output surface, a third input / output surface, and a fourth input / output surface provided at one end of the core pattern; a fifth input / output surface, a sixth input / output surface, a seventh input / output surface, and an eighth input / output surface provided at the other end of the core pattern; a first transmission section connected to the first input / output surface; a second transmission section connected to the second input / output surface; a third transmission section connected to the third input / output surface; a fourth transmission section connected to the fourth input / output surface; a fifth transmission section connected to the fifth input / output surface; a sixth transmission section connected to the sixth input / output surface; a seventh transmission section connected to the seventh input / output surface; and an eighth transmission section connected to the eighth input / output surface; a first branch section that branches the second transmission section; a second branch section that branches the fourth transmission section; a third branch section that branches the sixth transmission section, and a fourth branch section that branches the eighth transmission section, a first intersection section that connects the first transmission section to the third branch section and connects the first branch section to the fifth transmission section, a second intersection section that connects the first branch section to the fourth branch section and connects the second branch section to the third branch section, and a third intersection section that connects the second branch section to the seventh transmission section and connects the third transmission section to the fourth branch section, wherein when two straight lines that are orthogonal to each other in the plane are defined as a first straight line and a second straight line, a relationship of line symmetry is established between the first input / output surface, the second input / output surface, the fifth input / output surface, and the sixth input / output surface, and the third input / output surface, the fourth input / output surface, the seventh input / output surface, and the eighth input / output surface, with the first straight line as an axis of symmetry, an optical waveguide characterized in that a relationship of line symmetry exists between the first input / output surface, the second input / output surface, the third input / output surface, and the fourth input / output surface and the fifth input / output surface, the sixth input / output surface, the seventh input / output surface, and the eighth input / output surface, with the second straight line as an axis of symmetry.

2. An optical waveguide as described in claim 1, wherein a relationship of line symmetry with the first straight line as an axis of symmetry exists between the linear shape of the first branching portion and the linear shape of the second branching portion, and between the linear shape of the third branching portion and the linear shape of the fourth branching portion, respectively; and a relationship of line symmetry with the second straight line as an axis of symmetry exists between the linear shape of the first branching portion and the linear shape of the third branching portion, and between the linear shape of the second branching portion and the linear shape of the fourth branching portion, respectively.

3. The optical waveguide according to claim 1 or 2, wherein the intersection angle of the first intersection portion, the intersection angle of the second intersection portion, and the intersection angle of the third intersection portion are 15° or more and 45° or less.

4. An optical waveguide according to claim 1 or 2, wherein the first intersection, the second intersection and the third intersection have low refractive index portions across which incident light crosses.

5. The optical waveguide according to claim 4, wherein the thickness of said low refractive index portion in the direction in which said light is incident is 1.0 μm or more and 4.0 μm or less.

6. An optical waveguide according to claim 1 or 2, wherein the width of each of the second incident / exit surface, the fourth incident / exit surface, the sixth incident / exit surface and the eighth incident / exit surface is 20 μm or more and 55 μm or less.

7. The optical waveguide according to claim 6, wherein the core pattern includes a curved portion, and the bending radius of the curved portion is 5 mm or more and 15 mm or less.

8. The optical waveguide according to claim 7, wherein said curved portion is shaped along a clothoid curve.

9. An optical waveguide according to claim 1 or 2, comprising a laminate comprising: a core layer including the core pattern; a first clad layer laminated on one surface of the core layer; and a second clad layer laminated on the other surface of the core layer.

10. The optical waveguide according to claim 9, wherein said laminate is dimensionally symmetrical about a plane parallel to said plane and passing through the middle of the thickness of said core layer.

11. The optical waveguide according to claim 9, wherein the laminate is entirely made of a resin material.

12. An optical wiring component comprising: an optical waveguide according to claim 1 or 2; a first optical fiber connected to the second input / output surface; a second optical fiber connected to the fourth input / output surface; a third optical fiber connected to the fifth input / output surface; a fourth optical fiber connected to the sixth input / output surface; a fifth optical fiber connected to the eighth input / output surface; and a sixth optical fiber connected to the seventh input / output surface.

13. An optical wiring component as described in claim 12, comprising: a first light-emitting unit that causes light to be incident on the core pattern via the first optical fiber; a first light-receiving unit that receives light emitted from the core pattern via the second optical fiber; a second light-receiving unit that receives light emitted from the core pattern via the third optical fiber; a second light-emitting unit that causes light to be incident on the core pattern via the fourth optical fiber; a third light-receiving unit that receives light emitted from the core pattern via the fifth optical fiber; and a third light-emitting unit that causes light to be incident on the core pattern via the sixth optical fiber.

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