Optical systems and optical connectors

Abstract

The present invention provides an optical system and optical connector that can increase the number of optical systems that can be arranged in a fixed area. [Solution] The optical system 1 comprises: reflective surfaces R1a and R1c arranged at predetermined angles with respect to a first plane P1 and a second plane P1 that are substantially orthogonal to each other, and arranged sequentially at predetermined intervals in a first direction away from the second plane P2; two first lenses 21a and 21c, respectively, arranged between the first plane P1 and the reflective surfaces R1a and R1c, forming first focal points F1a and F1c on the first plane P1 side; and two second lenses 22a and 22c, respectively, arranged at predetermined intervals in a second direction parallel to the first plane P1 and perpendicular to the first direction, at a position on the second plane P2 side of the reflective surface R1a, forming second focal points F2a and F2c on the second plane P2 side.

Description

Technical Field

[0001] The present invention relates to an optical system that transmits light between an optical fiber and a light emitting element or a light receiving element, and an optical connector using the same.

Background Art

[0002] Conventionally, optical transmission systems that transmit optical signals using optical fibers have been used in various communication systems. For example, in a data center where a large number of servers are installed, adjacent servers are connected by optical fibers for data transfer. By using multiple cores for optical signal transmission, it is possible to increase the speed and capacity of data transmission. Such a configuration with multiple cores can be realized by using a multi-core optical fiber in which multiple cores are arranged in one optical fiber, or by bundling multiple single-core optical fibers and using them.

[0003] In such an optical transmission system, an optical connector is used to convert an electrical signal into an optical signal and incident it on the optical fiber, or to receive the optical signal emitted from the optical fiber and convert it into an electrical signal. An optical system for transmitting an optical signal between the optical fiber and the light emitting element or the light receiving element is arranged in the optical connector.

[0004] Patent Document 1 below describes an optical connector in which a plurality of optical elements (light emitting elements) and a plurality of optical fibers are arranged in one-to-one correspondence. For example, two optical elements are arranged side by side in the optical axis direction of the optical fiber, and two optical fibers are arranged side by side in the optical axis direction of these optical elements. Light from one optical element is reflected by the first reflection surface toward one optical fiber, and light from the other optical element is reflected by a second reflection surface different from the first reflection surface toward the other optical fiber. Further, two lenses facing the two optical elements respectively and two lenses facing the incident end faces of the two optical fibers respectively are arranged. The same configuration as described above is arranged in a plurality side by side in a direction perpendicular to the two optical axis directions.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-124418 [Overview of the project] [Problems that the invention aims to solve]

[0006] In data systems, increasing the number of optical systems installed on a single server increases both data transmission speed and capacity. However, there are limitations to the area on a server where optical systems can be installed. Therefore, it is desirable to be able to arrange as many optical systems as possible within a given area.

[0007] In view of these problems, the present invention aims to provide an optical system and an optical connector that can increase the number of optical systems that can be arranged in a row in a certain area. [Means for solving the problem]

[0008] A first aspect of the present invention relates to an optical system for transmitting optical signals. The optical system according to this aspect comprises: first and second reflective surfaces arranged at predetermined angles with respect to a first and second plane which are substantially orthogonal to each other, and arranged sequentially at predetermined intervals in a first direction away from the second plane; two first lenses arranged between the first plane and the first and second reflective surfaces, each forming a first focal point on the first plane side; and two second lenses arranged at predetermined intervals in a second direction parallel to the first plane and perpendicular to the first direction, at a position on the second plane side of the first reflective surface, each forming a second focal point on the second plane side. The end faces of two cores for optical transmission are positioned at the two second focal points, and two light-emitting elements or two photodetectors are positioned at the two first focal points, respectively. In the first direction, a first optical path for transmitting the optical signal via the first reflective surface is formed between the first lens at the front and one of the two second lenses, and a second optical path for transmitting the optical signal via the second reflective surface is formed between the first lens at the back and the other of the two second lenses in the first direction. The first reflective surface is positioned in a region that does not interfere with the second optical path.

[0009] According to the optical system of this embodiment, since two light-emitting elements or two light-receiving elements are arranged at a predetermined interval in the first direction, the width of the substrate on which these elements are mounted in the second direction can be reduced. Therefore, the number of optical systems that can be arranged side by side in the second direction for a given area can be increased, and as a result, data transmission can be made faster and with a larger capacity.

[0010] A second aspect of the present invention relates to an optical connector. The optical connector according to this aspect comprises an optical system according to the first aspect, at least one optical fiber constituting the plurality of cores, the plurality of light-emitting elements or the plurality of light-receiving elements, and a support member that supports the optical system, the optical fiber, and the plurality of light-emitting elements or the plurality of light-receiving elements.

[0011] According to the optical connector of this embodiment, since the optical system according to the first embodiment is used, the same effects as in the first embodiment can be achieved. [Effects of the Invention]

[0012] As described above, the present invention provides an optical system and an optical connector that can increase the number of optical systems that can be arranged in a certain area.

[0013] The effects and significance of the present invention will become even clearer from the description of the embodiments shown below. However, the embodiments shown below are merely examples of how to implement the present invention, and the present invention is not limited in any way to those described in the embodiments below. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a diagram showing the configuration of the optical system according to Embodiment 1. [Figure 2] Figure 2 is a perspective view showing the configuration of the support member according to Embodiment 1. [Figure 3] Figure 3 is a plan view showing the configuration of the support member according to Embodiment 1. [Figure 4] Figure 4 is a schematic perspective view showing the configuration of the light guide member according to Embodiment 1. [Figure 5] Figure 5 is a perspective view showing the configuration of an optical connector according to Embodiment 1. [Figure 6] Figure 6 is a schematic cross-sectional view showing the configuration of an optical connector according to Embodiment 1. [Figure 7] Figures 7(a) to 7(c) schematically show how light propagates inside the light guide member according to Embodiment 1. [Figure 8] Figures 8(a) to 8(c) are graphs showing the results of simulations of the light intensity distribution at the incident end face of a predetermined core according to Embodiment 1. [Figure 9]Figs. 9(a) to (c) are graphs showing the results obtained by simulation of the light intensity distribution at the incident end face of a predetermined core according to Embodiment 1. [Figure 10] Fig. 10 is a cross-sectional view schematically showing the configuration of an optical connector according to Modified Example 1 of Embodiment 1. [Figure 11] Fig. 11 is a cross-sectional view schematically showing the configuration of an optical connector according to Modified Example 2 of Embodiment 1. [Figure 12] Fig. 12 is a cross-sectional view schematically showing the configuration of an optical connector according to Embodiment 2. [Figure 13] Fig. 13 is a perspective view schematically showing the configuration of a light guiding member according to Embodiment 2. [Figure 14] Figs. 14(a) to (d) are diagrams schematically showing how each light propagates inside the light guiding member according to Embodiment 2. [Figure 15] Fig. 15 is a cross-sectional view schematically showing the configuration of an optical connector according to Embodiment 3. [Figure 16] Fig. 16 is a perspective view schematically showing the configuration of a light guiding member according to Embodiment 3. [Figure 17] Figs. 17(a) to (e) are diagrams schematically showing how each light propagates inside the light guiding member according to Embodiment 3. [Figure 18] Fig. 18 is a cross-sectional view schematically showing the configuration of an optical connector according to a modified example of Embodiment 3. [Figure 19] Figs. 19(a) to (e) are diagrams schematically showing how each light propagates inside the light guiding member according to a modified example of Embodiment 3. [Figure 20] Fig. 20 is a cross-sectional view schematically showing the configuration of an optical connector according to Embodiment 4. [Figure 21] Fig. 21 is a cross-sectional view schematically showing the configuration of an optical connector according to Embodiment 5. [Figure 22] Fig. 22 is a cross-sectional view schematically showing the configuration of an optical connector according to Embodiment 6. [Figure 23]Figure 23 is a schematic perspective view showing the configuration of the light guide member according to Embodiment 6. [Figure 24] Figures 24(a) to (c) schematically show how each light propagates inside the light guide member according to Embodiment 6. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the figures. For convenience, each figure is labeled with mutually orthogonal X, Y, and Z axes. The positive Y-axis direction is the height direction of the optical system 1 and the optical connector 2, and the X-axis direction is the width direction of the optical system 1 and the optical connector 2. The positive Z-axis direction, the X-axis direction, and the Y-axis direction correspond to the "first direction," "second direction," and "third direction" described in the claims, respectively.

[0016] <Embodiment 1> In Embodiment 1, the first lenses 21a and 21c may correspond to the "two first lenses" described in the claims. In this case, the second lenses 22a and 22c may correspond to the "two second lenses" described in the claims, and the reflective surfaces R1a and R1c may correspond to the "first and second reflective surfaces" described in the claims, respectively. Also in Embodiment 1, the first lenses 21b and 21d may also correspond to the "two first lenses" described in the claims. In this case, the second lenses 22b and 22d may correspond to the "two second lenses" described in the claims, and the reflective surfaces R1b and R1d may correspond to the "first and second reflective surfaces" described in the claims, respectively.

[0017] Figure 1 is a perspective view showing the configuration of the optical system 1 according to Embodiment 1. Figures 2 and 3 are a perspective view and a plan view, respectively, showing the configuration of the support member 10 according to Embodiment 1.

[0018] As shown in Figure 1, in Embodiment 1, three optical systems 1 are arranged in a line along the X-axis. Each optical system 1 comprises a support member 10 and a light guide member 20. Here, one support member 10 common to the three optical systems 1 is used. The support member 10 is made of, for example, silicon. The outer shape of the support member 10 is formed by etching a cubic prototype of the support member 10.

[0019] As shown in Figures 2 and 3, the support member 10 has a rectangular shape that is elongated in the Z-axis direction when viewed from above. The lower surface of the support member 10 is a plane that is parallel to the XZ plane over its entire length. The upper surface 11 of the support member 10 on the positive Z-axis side is higher than the upper surface 12 of the support member 10 on the negative Z-axis side. Multiple wirings 13 that will be connected to the substrate 40 (see Figure 5), which will be described later, are arranged on the upper surface 11 by thin film formation. Multiple wirings 13 are arranged for each optical system 1 in Figure 1. The wirings 13 in each group have a similar layout to each other.

[0020] Three recesses 15 are formed at the Z-axis negative end of the upper surface 11. The three recesses 15 are identical in shape to each other. The three recesses 15 are provided within the range of the three optical systems 1 in Figure 1. Each recess 15 is open on the Z-axis negative side. When viewed in the Z-axis positive direction, each recess 15 is rectangular in shape. That is, each recess 15 has a bottom surface 15a parallel to the XZ plane and two inner surfaces facing each other in the X-axis direction and parallel to the YZ plane. The bottom surface 15a constitutes the mounting surface on which the light guide member 20 in Figure 1 is installed. The Z-axis positive inner surface of each recess 15 is a plane parallel to the XY plane.

[0021] Three fiber support sections 14 are positioned on the upper surface 12 on the negative Z-axis side. The three fiber support sections 14 are provided within the range of the three optical systems 1 shown in Figure 1. Each fiber support section 14 has a valley shape of a certain depth that extends in the Z-axis direction. When viewed in the Z-axis direction, each valley shape is V-shaped. The deepest part of the valley shape extends parallel to the Z-axis, and two inclined surfaces are connected to this deepest part. The angle between each inclined surface and the XZ plane is the same. This angle is set to, for example, 35°. This allows the valley shape of the fiber support section 14 to be formed accurately at a predetermined depth by etching, in relation to the crystal orientation of silicon.

[0022] Three light guide members 20 are fitted into the three recesses 15 in Figure 2, and these light guide members 20 are placed on the bottom surface 15a of these recesses 15. This constitutes three optical systems 1, as shown in Figure 1. Each light guide member 20 is fixed to the support member 10 by applying adhesive to the boundary between each light guide member 20 and the recess 15.

[0023] Figure 4 is a schematic perspective view showing the configuration of the light guide member 20.

[0024] The light guide member 20 is made of a material with high light transmittance. The light guide member 20 has a rectangular parallelepiped shape that is long in the Z-axis direction. Four first lenses 21a to 21d are integrally arranged on the positive Y-axis side of the light guide member 20, and four second lenses 22a to 22d are integrally arranged on the negative Z-axis side of the light guide member 20. The four first lenses 21a to 21d and the four second lenses 22a to 22d are made of refractive lenses.

[0025] The four first lenses 21a to 21d are collimator lenses, and the four second lenses 22a to 22d are also collimator lenses. The four first lenses 21a to 21d are aligned in a straight line along the Z-axis. The four second lenses 22a to 22d are positioned at the intersections of two straight lines parallel to the Y-axis and two straight lines parallel to the X-axis. The spacing between the second lenses aligned along the X-axis is equal to the spacing between the second lenses aligned along the Y-axis. The four first lenses 21a to 21d are positioned in the same location along the X-axis as the two second lenses 22a and 22b on the positive X-axis side.

[0026] The light guide member 20 is constructed by joining three parts 20a to 20c with a transparent adhesive. The positive Z-axis side of part 20a is an inclined surface tilted at an angle θ1 with respect to the XZ plane, and the negative Z-axis side of part 20c is an inclined surface tilted at an angle θ1 with respect to the XZ plane. Therefore, the two Z-axis sides of part 20b are also inclined surfaces tilted at an angle θ1 with respect to the XZ plane. In Embodiment 1, the tilt angle θ1 is set to 45°.

[0027] A planar reflective surface R0 is positioned on the joint surface 31a of parts 20a and 20b, and planar reflective surfaces R1c and R1d are positioned on the joint surface 31b of parts 20b and 20c. Reflective surface R0 is perpendicular to the YZ plane. Reflective surfaces R1b and R1c are tilted by a few degrees around the Y axis from their perpendicular position to the YZ plane so that they face the second lenses 22c and 22d.

[0028] The reflective surface R0 is formed, for example, by creating a step of a certain depth that is recessed inward (in the negative Z-axis direction) in the region of the inclined surface of part 20a corresponding to the reflective surface R0, and by depositing a highly reflective metal material onto this step. The depth of this step may be approximately the thickness of the reflective surface R0. Similarly, the reflective surfaces R1c and R1d are formed, for example, by creating a step that is recessed inward (in the negative Z-axis direction) in the region of the inclined surface on the positive Z-axis side of part 20b corresponding to the reflective surfaces R1c and R1d, and by depositing a highly reflective metal material onto these steps. As described above, the depths of these steps are adjusted so that the depth on the positive X-axis side is greater than the depth on the negative X-axis side, so that the reflective surfaces R1c and R1d are tilted around the Y-axis.

[0029] With the reflective surfaces R0, R1c, and R1d thus formed, parts 20a to 20c are joined together with a transparent adhesive. Furthermore, the first lenses 21a to 21d and the second lenses 22a to 22d are formed in their corresponding positions by printing or the like. The first lenses 21a and 21b are placed on the upper surface of part 20a, and the first lenses 21c and 21d are placed on the upper surface of part 20b. The second lenses 22a to 22d are placed on the negative Z-axis side of part 20a.

[0030] The parts 20a to 20c of the light guide member 20 are formed from, for example, high-percentage glass. In this case, the first lenses 21a, 21b and the second lenses 22a to 22d may be integrally formed on part 20a by glass molding, and the first lenses 21c and 21d may be integrally formed on part 20b by glass molding. Alternatively, the parts 20a to 20c of the light guide member 20 may be formed from resin, and the first lenses 21a to 21d and the second lenses 22a to 22d may be integrally formed on the corresponding parts using resin material. Furthermore, the parts 20a to 20c of the light guide member 20 may be formed from light-transmitting silicon, and the first lenses 21a to 21d and the second lenses 22a to 22d may be integrally formed on the corresponding parts by etching the silicon substrate.

[0031] In the configuration shown in Figure 4, the optical axes of the two second lenses 22a and 22b on the positive X-axis side are parallel to the Z-axis. In contrast, the optical axes of the two second lenses 22c and 22d on the negative X-axis side are tilted from being parallel to the Z-axis to being parallel to the XZ plane. That is, the optical axes of the first lenses 21c and 21d are bent by the reflective surfaces R1c and R1d, which are tilted by a few degrees around the Y-axis as described above, from being parallel to the Z-axis to being tilted by a few degrees in the negative X-axis direction, and then reach the second lenses 22c and 22d. The second lenses 22c and 22d then bend these optical axes, which are tilted in the negative X-axis direction, by a few degrees to be parallel to the Z-axis, guiding them in the negative Z-axis direction. In order to achieve this optical effect, the optical axes of the two second lenses 22c and 22d on the negative X-axis side are tilted from being parallel to the Z-axis to being parallel to the XZ plane.

[0032] Figure 5 is a perspective view showing the configuration of the optical connector 2 according to Embodiment 1.

[0033] Three optical systems 1 are combined with three substrates 40 and three optical fibers 50 to form an optical connector 2. The three substrates 40 are placed on the upper surface 11 of the support member 10 so as to cover the areas of the first lenses 21a to 21d of the three light guide members 20, which are mounted in the three recesses 15 shown in Figure 2.

[0034] At this time, each terminal located on the underside of the circuit board 40 overlaps with the end of the corresponding wiring 13. Bumps (solder) are placed between each terminal and the end of the corresponding wiring 13, thereby electrically and mechanically joining each terminal and the end of the corresponding wiring 13. In this way, the three circuit boards 40 are placed on the upper surface 11 of the support member 10. The area of ​​the upper surface 11 where the circuit boards 40 overlap constitutes the mounting surface of the circuit boards 40.

[0035] The three optical fibers 50 are each installed in three fiber support sections 14 formed on the upper surface 12 of the support member 10 on the negative Z-axis side. Each optical fiber 50 is a multicore fiber having four cores 51a to 51d (see Figure 6). Each of the cores 51a to 51d is a single-mode core. Therefore, each of the cores 51a to 51d has high coupling efficiency with light having a Gaussian distribution of light intensity.

[0036] Each optical fiber 50 is installed in the corresponding fiber support portion 14 such that the four cores 51a to 51d located on the Z-axis positive end face face the four second lenses 22a to 22d of the light guide member 20. At this time, an adhesive such as ultraviolet-curing resin is applied between each optical fiber 50 and the valley shape of the corresponding fiber support portion 14, thereby fixing each optical fiber 50 to the corresponding fiber support portion 14. In this way, the ends of the three optical fibers 50 are installed on the upper surface 12 of the support member 10.

[0037] In the optical connector 2 for transmitting optical signals to the optical fiber 50, four light-emitting elements are arranged on the underside of the substrate 40. The optical signals emitted from these four light-emitting elements are incident on the four cores 51a to 51d of the optical fiber 50 via the reflective surfaces R0, R1c, and R1d inside the light guide member 20. On the other hand, in the optical connector 2 for receiving optical signals from the optical fiber 50, four light-receiving elements are arranged on the underside of the substrate 40. The optical signals emitted from the four cores 51a to 51d of the optical fiber 50 are received by the four light-receiving elements arranged on the underside of the substrate 40 via the reflective surfaces R0, R1c, and R1d inside the light guide member 20.

[0038] Figure 6 is a schematic cross-sectional view showing the configuration of the optical connector 2.

[0039] Figure 6 shows a cross-sectional view of the optical connector 2 when it has only one optical system 1. Here, four light-emitting elements 41a to 41d are arranged in the Z-axis direction on the substrate 40. The lower part of Figure 6 shows a cross-section of the optical connector 2 when it is cut in a plane that includes the center positions of these light-emitting elements 41a to 41d and is parallel to the YZ plane. When the optical connector 2 has multiple optical systems 1 as shown in Figure 5, the cross-sectional view of each part of the optical system 1 is the same as in Figure 6.

[0040] The top right figure in Figure 6 shows the configuration of the substrate 40, enclosed by the dashed-dotted rectangle in the bottom right of Figure 6, when viewed in the positive Y-axis direction. The top left figure in Figure 6 shows the configuration of the optical fiber 50, enclosed by the dashed-dotted rectangle in the bottom left of Figure 6, when viewed in the negative Z-axis direction. The second figure from the right in the top row of Figure 6 shows the configuration of the light guide member 20 (four first lenses 21a to 21d), enclosed by the dashed-dotted rectangle in the bottom right of Figure 6, when viewed in the negative Y-axis direction. The second figure from the left in the top row of Figure 6 shows the configuration of the light guide member 20 (four second lenses 22a to 22d), enclosed by the dashed-dotted rectangle in the second figure from the left in the bottom row of Figure 6, when viewed in the positive Z-axis direction.

[0041] The height of the upper surface of the light guide member 20 is lower than the height of the upper surface 11 of the support member 10. The substrate 40 is placed on the upper surface of the light guide member 20 and is joined to the upper surface 11 by bumps as described above. As described above, the inclination angle θ1 of the joining surfaces 31a and 31b (reflective surfaces R0, R1c, R1d) is 45°. That is, the reflective surfaces R0, R1c, and R1d are positioned at an inclination of only 45° with respect to the mutually orthogonal first plane P1 and second plane P2. The first plane P1 is parallel to the XZ plane, and the second plane P2 is parallel to the XY plane. The first plane P1 and the second plane P2 only need to be substantially orthogonal. Also, the inclination angle θ1 only needs to be substantially 45°.

[0042] The first lenses 21a to 21d are positioned between the bonding surfaces 31a and 31b (reflecting surfaces R0, R1c, and R1d) and the second plane P2. The first focal points F1a to F1d of the first lenses 21a to 21d are aligned in the Z-axis direction and positioned at different locations on the first plane P1. The distance from the first lenses 21a to 21d to the first plane P1 is equal to the focal length of each of the first lenses 21a to 21d. The focal lengths of these first lenses 21a to 21d are equal to each other. The substrate 40 is installed so that the light-emitting elements 41a to 41d are positioned at these first focal points F1a to F1d, respectively. The first focal points F1a to F1d are positioned at the center of the light-emitting elements 41a to 41d, respectively. Therefore, the light-emitting elements 41a to 41d are aligned in the Z-axis direction.

[0043] The second lenses 22a to 22d are positioned between the bonding surfaces 31a and 31b (reflecting surfaces R0, R1c, and R1d) and the second plane P2. The second focal points F2a to F2d of the second lenses 22a to 22d are positioned at different locations on the second plane P2. That is, the distance from the second lenses 22a to 22d to the second plane P2 is equal to the focal length of each second lens 22a to 22d. The focal lengths of these second lenses 22a to 22d are equal to each other. Optical fibers 50 are installed so that the end faces of the optical transmission cores 51a to 51d are positioned at these second focal points F2a to F2d, respectively. The second focal points F2a to F2d are positioned at the center of the end faces of the cores 51a to 51d, respectively.

[0044] In Embodiment 1, the first lens 21a, the reflective surface R0, and the second lens 22a form a first optical signal transmission path (optical path of light L1a) between the light-emitting element 41a and the core 51a, the first lens 21b, the reflective surface R0, and the second lens 22b form a second optical signal transmission path (optical path of light L1b) between the light-emitting element 41b and the core 51b, the first lens 21c, the reflective surface R1c, and the second lens 22c form a third optical signal transmission path (optical path of light L1c) between the light-emitting element 41c and the core 51c, and the first lens 21d, the reflective surface R1d, and the second lens 22d form a fourth optical signal transmission path (optical path of light L1d) between the light-emitting element 41d and the core 51d.

[0045] Each transmission path (optical path of each light) between each reflective surface and cores 51a to 51d is parallel to the XZ plane. In a plan view when viewed in the negative Y direction, the first transmission path (optical path of light L1a) and the second transmission path (optical path of light L1b) overlap each other except for the area between the light-emitting elements 41a and 41b. Also, in a plan view when viewed in the negative Y direction, the third transmission path (optical path of light L1c) and the fourth transmission path (optical path of light L1d) move away from the first transmission path (optical path of light L1a) and the second transmission path (optical path of light L1b) in the negative X direction as they proceed in the negative Z direction, due to the inclination of the reflective surfaces R1c and R1d around the Y axis.

[0046] For example, the mode field diameter (MFD) of cores 51a to 51d is approximately 6 to 8 μm. Also, for example, the distance between cores 51a (core 51b) and core 51c (core 51d) aligned in the X-axis direction (center-to-center distance) is approximately 40 to 50 μm, and the distance between cores 51a (core 51c) and core 51b (core 51d) aligned in the Y-axis direction (center-to-center distance) is also approximately 40 to 50 μm. The second lenses 22a to 22d are arranged in the same layout and with the same spacing (center-to-center distance) as cores 51a to 51d. The distance between light-emitting elements 41a and 41b and the distance between first lenses 21a and 21b is equal to the distance between cores 51a and 51b, and the distance between light-emitting elements 41c and 41d and the distance between first lenses 21c and 21d is equal to the distance between cores 51c and 51d.

[0047] Each of the light-emitting elements 41a to 41d consists of a surface-emitting laser such as a VCSEL. These light-emitting elements 41a to 41d are of the same type and have equal height (thickness). Each of the light-emitting elements 41a to 41d emits light L1a to L1d (optical signals) in the negative Y-axis direction with a radiation angle of approximately NA 0.1 to 0.2. The wavelengths of the light L1a to L1d are in the range of 850 nm to 1550 nm. The light-emitting elements 41a to 41d may be other light-emitting elements other than surface-emitting lasers. Each of the light-emitting elements 41a to 41d is driven by its respective drive signal, which is modulated according to the transmitted data. These drive signals are input from the circuit section to each of the light-emitting elements 41a to 41d via wiring 13.

[0048] The light L1a to L1d emitted from each of the light-emitting elements 41a to 41d enters the first lenses 21a to 21d. As described above, since each of the light-emitting elements 41a to 41d is positioned at each of the first focal points F1a to F1d, each of the light L1a to L1d is made into parallel light by the first lenses 21a to 21d.

[0049] Subsequently, the light rays L1a to L1d are reflected in the negative Z-axis direction by the corresponding reflective surfaces R0, R1c, and R1d, propagate through the inside of the light guide member 20, and enter the corresponding second lenses 22a to 22d. As described above, since the end faces of the respective cores 51a to 51d are positioned at the respective second focal points F2a to F2d, each of the light rays L1a to L1d is focused onto the end faces of the corresponding cores 51a to 51d by the corresponding second lenses 22a to 22d. The beam diameter of the light rays L1a to L1d at the end faces of the cores 51a to 51d is approximately that of the MFD described above.

[0050] In this way, four optical paths (optical paths L1a to L1d) for transmitting optical signal L1 are formed, and optical signals L1a to L1d are transmitted between the light-emitting elements 41a to 41d and the cores 51a to 51d corresponding to each optical path. Here, since different optical signals can be transmitted simultaneously using four transmission systems, the transmission capacity of the optical signal can be increased.

[0051] Figures 7(a) to 7(c) schematically show how light L1a to L1d propagates inside the light guide member 20.

[0052] Figure 7(a) shows the incident state of light L1a to L1d on the second lenses 22a to 22d, Figure 7(b) shows the incident state of light L1a to L1d on the bonding surface 31a, and Figure 7(c) shows the incident state of light L1c and L1d on the bonding surface 31b. Figures 7(a) to (c) show the state of light L1a to L1d when the second lenses 22a to 22d and the bonding surfaces 31a and 31b are viewed in the positive Z-axis direction.

[0053] As shown in Figure 7(c), at the bonding surface 31b, light L1c and L1d, emitted from the light-emitting elements 41c and 41d respectively and parallelized by the first lenses 21c and 21d, respectively, are incident on the reflective surfaces R1c and R1d. These light L1c and L1d are reflected by the reflective surfaces R1c and R1d. At this time, the reflection direction of the light L1c and L1d is tilted a few degrees from the negative Z-axis direction to the negative X-axis direction, as shown by the dashed arrows, due to the inclination of the reflective surfaces R1c and R1d around the Y-axis.

[0054] Thus, because the direction of propagation of the reflected light L1c and L1d has a component in the negative X-axis direction, the light L1c and L1d pass through the region without a reflective surface on the negative X-axis side of the reflective surface R0 at the position of the bonding surface 31a in Figure 7(b). Subsequently, these light L1c and L1d travel through the inside of the light guide member 20 in the same direction and enter the corresponding second lenses 22c and 22d, as shown in Figure 7(a).

[0055] At this time, the light rays L1c and L1d are incident on the second lenses 22c and 22d in a direction of propagation that is slightly inclined in the X-axis direction relative to the Z-axis direction. However, since the second lenses 22c and 22d are tilted around the Y-axis as described above, the optical axes of the light rays L1c and L1d after passing through the second lenses 22c and 22d are corrected to be parallel to the Z-axis. These optical axes align with the optical axes of the corresponding cores 51c and 51d. In this way, the light rays L1c and L1d are focused by the second lenses 22c and 22d towards the center of the cores 51c and 51d.

[0056] Furthermore, at the bonding surface 31a, as shown in Figure 7(b), the light L1a and L1b emitted from the light-emitting elements 41a and 41b, respectively, and parallelized by the first lenses 21a and 21b, respectively, are incident on the reflective surface R0. These light L1a and L1b are reflected by the reflective surface R0. Unlike the reflective surfaces R1c and R1d, the reflective surface R0 is not tilted around the Y axis, so the reflection direction of the light L1a and L1b is parallel to the Z axis.

[0057] Subsequently, these light rays L1a and L1b travel through the inside of the light guide member 20 in the negative Z-axis direction and enter the corresponding second lenses 22a and 22b, as shown in Figure 7(a). The optical axes of these second lenses 22a and 22b are parallel to the Z-axis and are aligned with the optical axes of the incident light rays L1a and L1b. Furthermore, the optical axes of the second lenses 22a and 22b are also aligned with the optical axes of the corresponding cores 51a and 51b. In this way, the light rays L1a and L1b are focused by the second lenses 22a and 22b towards the center of the cores 51a and 51b.

[0058] In Embodiment 1, as shown in Figure 7(b), a common reflective surface R0 is used for light sources L1a and L1b. However, the region enclosed by the rectangular dashed line within the reflective surface R0 is the actual reflective surface R1a and R1b for light sources L1a and L1b. In other words, the reflective surfaces R1a and R1b for light sources L1a and L1b are part of the common reflective surface R0 that extends across a single plane.

[0059] Figures 8(a) to 8(c) are graphs showing the simulation results of the intensity distribution of light L1b at the incident end face (second plane P2) of core 51b, one of the four cores 51a to 51d in Figure 6.

[0060] As described above, in the configuration of Figure 6, the inclination angle θ1 is set to 45°, and the optical axes of the paired first lens 21b, second lens 22b, and core 51b are aligned with each other. Therefore, the intensity distribution of light L1b at the incident end face of core 51b is a nearly identical Gaussian distribution over the entire circumference, as shown in Figures 8(a) to (c). Consequently, as described above, when light L1b is focused at the incident end face of the single-mode core 51b with a beam diameter approximately equal to that of the MFD of core 51b, the optical coupling efficiency between light L1b and core 51b increases. Therefore, optical loss when light L1b is incident from optical system 1 to core 51b can be effectively suppressed.

[0061] Furthermore, in the configuration shown in Figure 6, the optical axes of the paired first lens 21a, second lens 22a, and core 51a are aligned with each other. As a result, the intensity distribution of light L1a at the incident end face of core 51a is the same as in Figures 8(a) to (c). Therefore, as described above, the optical coupling efficiency between the light L1a and core 51a is also increased, and optical loss when light L1a is incident from optical system 1 to core 51a can be effectively suppressed.

[0062] Figures 9(a) to (c) are graphs showing the simulation results of the intensity distribution of light L1d at the incident end face (second plane P2) of core 51d, one of the four cores 51a to 51d in Figure 6.

[0063] As described above, in the configuration shown in Figure 6, the light L1d is incident on the second lens 22d in a direction that is slightly tilted towards the X-axis from being parallel to the Z-axis. Therefore, although the intensity distribution of light L1d at the incident end face of core 51d is slightly deviated from a Gaussian distribution, an intensity distribution close to a Gaussian distribution is obtained. In addition, although the peak intensity of light L1d at the incident end face of core 51d is slightly lower than in Figures 8(a) to (c), a relatively high peak intensity is obtained.

[0064] Therefore, according to the configuration of Embodiment 1, it is possible to transmit a large-capacity optical signal through four transmission systems while suppressing the loss of optical signals.

[0065] <Effects of Embodiment 1> According to Embodiment 1, the following effects are achieved.

[0066] As shown in Figures 1, 4, 6, and 7(a)-(c), the optical system 1 is arranged at a predetermined angle with respect to a first plane P1 and a second plane P2 that are substantially orthogonal to each other, and consists of reflective surfaces R1a (first reflective surface) and R1c (second reflective surface) arranged sequentially at predetermined intervals in a first direction (positive Z-axis direction) away from the second plane, and the relationship between the first plane P1 and the reflective surfaces R1a (first reflective surface) and R1c (second reflective surface) The device comprises two first lenses 21a and 21c positioned between the two reflective surfaces, forming first focal points F1a and F1c on the first plane P1 side, and two second lenses 22a and 22c positioned on the second plane P2 side of the reflective surface R1a (first reflective surface), at a predetermined interval in a second direction (X-axis direction) parallel to the first plane P1 and perpendicular to the first direction (positive Z-axis direction), forming second focal points F2a and F2c on the second plane P2 side. The end faces of two optical transmission cores 51a and 51c are positioned at the two second focal points F2a and F2c, respectively, and two light-emitting elements 41a and 41c are positioned at the two first focal points F1a and F1c, respectively. In the first direction (positive Z-axis direction), an optical path (first optical path) for optical signal L1a is formed between the front first lens 21a and the two second lenses 22a via a reflective surface R1a (first reflective surface). In the first direction (positive Z-axis direction), an optical path (second optical path) for optical signal L1c is formed between the rear first lens 21c and the other of the second lenses 22c via a reflective surface R1c (second reflective surface). The reflective surface R1a (first reflective surface) is positioned in a region that does not interfere with the optical path (second optical path) of optical signal L1c.

[0067] With this configuration, since the two light-emitting elements 41a and 41c are arranged at a predetermined interval in the first direction (positive Z-axis direction), the width of the substrate 40 on which these light-emitting elements 41a and 41c are mounted in the second direction (X-axis direction) can be reduced. Therefore, the number of optical systems 1 that can be arranged side by side in the second direction for a given area can be increased, and as a result, data transmission can be made faster and with a larger capacity.

[0068] As shown in Figures 4 and 7(b) and (c), when viewed in the first direction (positive Z-axis direction), the reflective surface R1a (first reflective surface) and the reflective surface R1c (second reflective surface) overlap in at least part, and the inclination of the reflective surface R1c (second reflective surface) around the Y-axis perpendicular to both the first direction (positive Z-axis direction) and the second direction (X-axis direction) is adjusted so that the optical path of light L1c (second optical path) passes outside the reflective surface R1a (first reflective surface).

[0069] With this configuration, interference of the optical path (second optical path) of light L1c with respect to the reflective surface R1a (first reflective surface) can be avoided by adjusting the inclination of the reflective surface R1c (second reflective surface).

[0070] As shown in Figures 1, 4, 6 and 7(a)-(c), the optical system 1 includes two other first lenses 21b, 21d positioned at a predetermined distance from the two first lenses 21a, 21c in a direction parallel to the first direction, two other second lenses 22b, 22d positioned at a predetermined distance from the two second lenses 22a, 22c in a third direction, and the other of the two other first lenses 21b, 21c that is closer in the first direction. The device further comprises a reflective surface R1b (third reflective surface) that forms an optical path for light L1b (third optical path) between one of the two other second lenses 22b, 22d (second lens 22b) and a reflective surface R1d (fourth reflective surface) that forms an optical path for light L1d (fourth optical path) between the other first lens 21d (the one further back in the first direction) and the other of the two other second lenses 22b, 22d (second lens 22d). The end faces of two other cores 51b, 51d for optical transmission are positioned at the second focal points F2b, F2d of the two other second lenses 22b, 22d, respectively, and two other light-emitting elements 41b, 41d are positioned at the first focal points F1b, F1d of the two other first lenses 21b, 21d, respectively. Among the reflective surfaces R1a to R1d (first to fourth reflective surfaces), the reflective surface that is closer to the front in the first direction than the other reflective surfaces is positioned in a region of the optical paths L1a to L1d (first to fourth optical paths) that does not interfere with the optical paths formed by the other reflective surfaces.

[0071] With this configuration, the two other light-emitting elements 41b and 41d are also arranged at a predetermined interval in the first direction, so that the width of the substrate 40 on which these light-emitting elements 41a to 41d are mounted does not increase in the second direction. In addition, since optical signals can be further transmitted through the optical paths of L1b and L1d (third and fourth optical paths), the speed and capacity of data transmission can be further increased.

[0072] As shown in Figure 6, the other second focal points F2b and F2d of the two other second lenses 22b and 22d are aligned in a third direction (Y-axis direction) with respect to the second focal points F2a and F2c of the two second lenses 22a and 22c.

[0073] This configuration allows for smooth handling of multicore fibers having four cores 51a to 51d.

[0074] As shown in Figures 4, 6, and 7(a)-(c), among the reflective surfaces R1a, R1c, R1b, and R1d (the first to fourth reflective surfaces), the two reflective surfaces R1a and R1b, which are closest in the first direction, are part of a common reflective surface R0 that extends in a single plane.

[0075] With this configuration, the reflective surfaces R1a and R1b are formed by a common reflective surface R0, thus simplifying the configuration of the optical system 1.

[0076] As shown in Figure 13, the two first lenses 21c, 21d and the two other first lenses 21a, 21b are arranged substantially in a straight line in the first direction.

[0077] This configuration allows for an effective reduction in the width of the substrate 40 in the second direction. Furthermore, when the light-emitting elements 41c, 41d, 41a, and 41b are positioned at two first focal points F1c, F1d and two other first focal points F1a, F1b, a linear array of light-emitting elements can be used.

[0078] As shown in Figure 6, the first foci F1a to F1d are formed on the first plane P1, and the second foci F2a to F2d are formed on the second plane P2.

[0079] With this configuration, since the light-emitting elements 41a to 41d only need to be placed on the first plane P1, identical light-emitting elements 41a to 41d having the same height can simply be mounted and arranged on a flat substrate 40. Furthermore, since the end faces of the cores 51a to 51d all need to be placed on the second plane P2, there is no need to adjust the position of these end faces of the cores 51a to 51d in the front-to-back direction (Z-axis direction). As described above, if the optical fiber 50 is a multi-core fiber and the end faces of multiple cores 51a to 51d are already included in the same plane, the end faces of these cores 51a to 51d can be easily placed at their respective second focal points F2a to F2d.

[0080] As shown in Figures 4 and 6, the reflective surfaces R0 (R1a, R1b), R1c, R1d, the first lenses 21a-21d, and the second lenses 22a-22d are integrally arranged on the light guide member 20.

[0081] With this configuration, the positional relationship between each reflective surface and the first lenses 21a-21d and the second lenses 22a-22d can be fixed, thus suppressing the loss of optical signals due to misalignment between these reflective surfaces and lenses. Furthermore, by installing the light guide member 20 on the support member 10, these reflective surfaces and lenses can be installed on the support member 10, thus simplifying the installation work of these reflective surfaces and lenses on the support member 10.

[0082] As shown in Figure 6, the reflective surfaces R1a to R1c are inclined at substantially 45° with respect to the first plane P1 and the second plane P2, and the optical paths L1a to L1d between each reflective surface and the second lenses 22a to 22d are parallel to the first plane P1.

[0083] With this configuration, when light-emitting elements 41a to 41d with a Gaussian distribution of emission intensity are arranged at each of the first focal points F1a to F1d, the intensity of the light L1a to L1d at each incident end face of the cores 51a to 51d can be made to approach a Gaussian distribution, as shown in Figures 8(a) to 9(d). This increases the coupling efficiency of the light L1a to L1d for each single-mode core 51a to 51d, and effectively suppresses the loss of light L1a to L1d (optical signal).

[0084] As shown in Figures 5 and 6, the optical connector 2 comprises an optical system 1, optical fibers 50 constituting a plurality of cores 51a to 51d, a plurality of light-emitting elements 41a to 41d, and a support member 10 that supports the optical system 1, the optical fibers 50, and the plurality of light-emitting elements 41a to 41d.

[0085] With this configuration, since the optical system 1 has a reduced width in the second direction (X-axis direction), more optical systems 1 can be arranged in the second direction on the optical connector 2, or if the optical connector 2 has one optical system 1, more optical connectors 2 can be arranged in the second direction.

[0086] As shown in Figure 6, the optical fiber 50 is a multicore fiber having multiple cores 51a to 51d.

[0087] With this configuration, by installing one optical fiber 50 on the support member 10, multiple cores 51a to 51d for transmitting optical signals can be arranged, and the end faces of these cores 51a to 51d can be positioned at multiple second focal points F2a to F2d on the second plane P2, respectively.

[0088] As described above, each of the multiple light-emitting elements 41a to 41d is a surface-emitting laser.

[0089] With this configuration, by using surface-emitting lasers with small emission angles as light-emitting elements 41a to 41d, the beam diameter of the light L1a to L1d incident on the first lenses 21a to 21d can be reduced. As a result, the effective diameter of each of the first lenses 21a to 21d can be reduced, and consequently, the increase in size of the optical system 1 and optical connector 2 in the first direction (Z-axis direction) can be suppressed.

[0090] As described above, it is preferable that the wavelength of light emitted from the multiple light-emitting elements 41a to 41d falls within the range of 850 nm to 1550 nm.

[0091] This allows for smooth transmission of optical signals while suppressing signal loss.

[0092] <Example of change 1> Figure 10 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to a modified example 1 of Embodiment 1.

[0093] Similar to Figure 6, Figure 10 also shows a cross-sectional view of the optical connector 2 when the optical connector 2 has only one optical system 1.

[0094] In Embodiment 1 described above, four light-emitting elements 41a to 41d were arranged on the substrate 40, but in Modification Example 1 of Figure 10, four light-receiving elements 42a to 42d are arranged on the substrate 40. The light-receiving elements 42a to 42d are, for example, PDs (photodetectors). These light-receiving elements 42a to 42d are of the same type and have equal height (thickness). The arrangement of the light-receiving elements 42a to 42d is the same as the arrangement of the light-emitting elements 41a to 41d in Figure 6. The configuration is the same as that shown in Figure 6, except that the light-emitting elements 41a to 41d are replaced with light-receiving elements 42a to 42d.

[0095] In this modified example, light signals L1a to L1d are emitted from the end faces of each core 51a to 51d. The emitted light signals L1a to L1d travel in the reverse direction of the optical path, similar to that in Figure 6, and are focused onto the photodetectors 42a to 42d. As a result, the photodetectors 42a to 42d output an electrical signal modulated according to the light signals L1a to L1d. This electrical signal is output to the circuit section via the wiring 13.

[0096] According to the configuration in Figure 10, although the mode of transmission and reception of optical signals differs, the same effects as in Embodiment 1 can be generally achieved. According to the configuration of Modified Example 1, an optical system 1 and an optical connector 2 for receiving optical signals via an optical fiber can be configured, and the width of the substrate 40 installed on the optical system 1 in the second direction (X-axis direction) can be reduced. Therefore, even in this configuration, the number of optical systems 1 and optical connectors 2 that can be arranged in a certain area can be increased.

[0097] <Example of change 2> Figure 11 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to a modified example 2 of Embodiment 1.

[0098] Similar to Figure 6, Figure 11 also shows a cross-sectional view of the optical connector 2 when the optical connector 2 has only one optical system 1. In modified example 2 of Figure 11, the distance between the light-emitting elements 41b and 41c is increased compared to the configuration in Figure 6, and consequently, the distance between the first lenses 21b and 21c is also increased. The other configurations in modified example 2 of Figure 11 are the same as those in the configuration in Figure 6.

[0099] According to the configuration of the modified example 2, part 20b in Figure 4 becomes longer in the Z-axis direction, and although the length of the light guide member 20 also becomes longer in the Z-axis direction, part 20b becomes easier to manufacture.

[0100] <Embodiment 2> In Embodiment 2, the first lenses 21c and 21d correspond to the "two first lenses" described in the claims, the second lenses 22c and 22d correspond to the "two second lenses" described in the claims, and the reflective surfaces R2c and R2d correspond to the "first and second reflective surfaces" described in the claims, respectively. Furthermore, in Embodiment 2, the first lenses 21a and 21b correspond to the "two other first lenses" described in the claims, the second lenses 22a and 22b correspond to the "two other second lenses" described in the claims, and the reflective surfaces R2a and R2b correspond to the "third reflective surface" and "fourth reflective surface" described in the claims, respectively.

[0101] Figure 12 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to Embodiment 2.

[0102] Similar to Figure 6, Figure 12 also shows a cross-sectional view of the optical connector 2 when the optical connector 2 has only one optical system 1.

[0103] In Embodiment 2, the arrangement of the cores 51a to 51d in the second plane P2 is different from that of Embodiment 1. Specifically, in Embodiment 2, the end of the optical fiber 50 is installed on the support member 10 rotated by 45° around the central axis of the optical fiber 50 from the state shown in Figure 6. For this reason, four second lenses 22a to 22d are arranged on the negative Z-axis side of the light guide member 20, opposite to the four cores 51a to 51d, and three bonding surfaces 32a to 32c are arranged inside the light guide member 20.

[0104] Figure 13 is a schematic perspective view showing the configuration of the light guide member 20 according to Embodiment 2.

[0105] The light guide member 20 is composed of four parts 20a to 20d. The parts 20a to 20d are joined together to form a rectangular parallelepiped-shaped light guide member 20. Joining surfaces 32a to 32c are formed between adjacent parts. The inclination angle θ1 of the joining surfaces 32a to 32c with respect to the XZ plane is 45°, as in the first embodiment described above.

[0106] The second lenses 22a to 22d are positioned on the negative Z-axis side of part 20a. The second lenses 22a and 22b are aligned in the Y-axis direction at the midpoint of part 20a in the X-axis direction, and the second lenses 22c and 22d are aligned in the X-axis direction at the midpoint of part 20a in the Y-axis direction. The second lenses 22a to 22d face the cores 51a to 51d, respectively. The first lenses 21a and 21b are positioned on the upper surface of part 20a, and the first lenses 21c and 21d are positioned on the upper surfaces of parts 20b and 20c, respectively. The first lenses 21a to 21d are aligned linearly in the Z-axis direction at the midpoint of the light guide member 20 in the X-axis direction.

[0107] Two reflective surfaces R2a and R2b are arranged on the joint surface 32a. When viewed in the Z-axis direction, the joint surface 32a is open in the center in the Y-axis direction, with flat reflective surfaces R2a and R2b arranged in a band shape below and above it. The reflective surfaces R2a and R2b are perpendicular to the YZ plane. The reflective surfaces R2a and R2b are formed, for example, by creating a step of a certain depth that is recessed inward (in the negative Z-axis direction) in the region corresponding to the reflective surfaces R2a and R2b on the positive Z-axis side surface (inclined surface) of part 20a, and depositing a highly reflective metallic material onto this step. The depth of this step may be about the same as the thickness of the reflective surface R0.

[0108] A reflective surface R2c is positioned on the bonding surface 32b. When viewed in the Z-axis direction, the bonding surface 32b is open on the positive and negative X-axis sides, and a flat reflective surface R2c is positioned in a band shape in the center in the X-axis direction. The reflective surface R2c is tilted by a few degrees around the Y-axis from a state perpendicular to the YZ plane so as to face the second lens 22c. The reflective surface R2c is formed, for example, by creating a step that is recessed inward (in the negative Z-axis direction) in the region corresponding to the reflective surface R2c on the positive Z-axis side surface (inclined surface) of part 20b, and depositing a highly reflective metallic material onto this step. As described above, the depth of this step is adjusted so that the depth on the positive X-axis side is greater than the depth on the negative X-axis side, so that the reflective surface R2c is tilted around the Y-axis.

[0109] On the bonding surface 32c, a flat reflective surface R2d is arranged in a band shape, in the same arrangement as the reflective surface R2c relative to the bonding surface 32b. The reflective surface R2d is tilted by a few degrees around the Y axis from a state perpendicular to the YZ plane so as to face the second lens 22d. The reflective surface R2d is formed, for example, by creating a step that is recessed inward (in the negative Z direction) in the region corresponding to the reflective surface R2d on the positive Z side (inclined surface) of part 20c, and depositing a highly reflective metallic material onto this step. As described above, the depth of this step is adjusted so that the depth on the negative X side is greater than the depth on the positive X side, so that the reflective surface R2d is tilted around the Y axis.

[0110] In the configuration shown in Figure 13, the optical axes of the second lenses 22a and 22b are parallel to the Z-axis. In contrast, the optical axes of the second lenses 22c and 22d are tilted around the Y-axis from a state parallel to the Z-axis. That is, the optical axis of the first lens 21c is bent by the reflective surface R2c, which is tilted by a few degrees around the Y-axis as described above, from a state parallel to the Z-axis to a state tilted by a few degrees in the negative X-axis direction, and reaches the second lens 22c. The second lens 22c then bends the optical axis, which is tilted in the negative X-axis direction in this way, by a few degrees to a state parallel to the Z-axis, guiding it in the negative Z-axis direction. In order to achieve this optical effect, the optical axis of the second lens 22c is tilted around the Y-axis from a state parallel to the Z-axis.

[0111] Furthermore, the optical axis of the first lens 21d is bent by a reflective surface R2d, which is tilted by a few degrees around the Y-axis as described above, from being parallel to the Z-axis to being tilted by a few degrees in the positive X-axis direction, and reaches the second lens 22d. The second lens 22d then bends the optical axis, which is tilted in the positive X-axis direction in this way, by a few degrees to be parallel to the Z-axis, guiding it in the negative Z-axis direction. In order to achieve this optical effect, the optical axis of the second lens 22d is tilted around the Y-axis from being parallel to the Z-axis.

[0112] The materials constituting parts 20a to 20d are the same as those used for parts 20a to 20c in Embodiment 1. Furthermore, the method for forming the first lenses 21a to 21d and the second lenses 22a to 22d on each part is also the same as in Embodiment 1.

[0113] Figures 14(a) to (d) schematically show how light L1a to L1d propagates inside the light guide member 20.

[0114] Figure 14(a) shows the incident state of light L1a to L1d on the second lenses 22a to 22d, Figure 14(b) shows the incident state of light L1a to L1d on the bonding surface 32a, Figure 14(c) shows the incident state of light L1c and L1d on the bonding surface 32b, and Figure 14(d) shows the incident state of light L1d on the bonding surface 32c. Figures 14(a) to (d) show the state of light l1a to L1d when the second lenses 22a to 22d and the bonding surfaces 32a to 32c are viewed in the positive Z-axis direction.

[0115] As shown in Figure 14(d), at the bonding surface 32c, light L1d emitted from the light-emitting element 41d and parallelized by the first lens 21d is incident on the reflective surface R2d. The light L1d is reflected by the reflective surface R2d. At this time, the reflection direction of the light L1d is tilted by a few degrees from the negative Z-axis direction to the positive X-axis direction, as shown by the dashed arrow, due to the inclination of the reflective surface R2d around the Y-axis.

[0116] Thus, because the direction of propagation of the reflected light L1d has a component in the positive X-axis direction, the light L1d passes through the region without a reflective surface on the positive X-axis side of the reflective surface R2c at the position of the bonding surface 32b in Figure 14(c). Subsequently, the light L1d continues to travel through the inside of the light guide member 20 in the same direction, passes through the region without reflective surfaces R2a and R2b at the bonding surface 32a in Figure 14(b), and enters the corresponding second lens 22d as shown in Figure 14(a).

[0117] At this time, light L1d enters the second lens 22d with a direction of propagation that is slightly inclined in the X-axis direction relative to the Z-axis direction. However, as described above, the second lens 22d is tilted around the Y-axis, so the optical axis of light L1d after passing through the second lens 22d is corrected to be parallel to the Z-axis. This optical axis aligns with the optical axis of the corresponding core 51d. In this way, light L1d is focused by the second lens 22d towards the center of the core 51d.

[0118] Furthermore, as shown in Figure 14(c), at the bonding surface 32b, light L1c emitted from the light-emitting element 41c and parallelized by the first lens 21c is incident on the reflective surface R2c. The light L1c is reflected by the reflective surface R2c. At this time, the reflection direction of the light L1c is tilted by a few degrees from the negative Z-axis direction to the negative X-axis direction, as shown by the dashed arrow, due to the inclination of the reflective surface R2c around the Y-axis. After that, the light L1c travels through the inside of the light guide member 20 in the same direction, passes through the region without reflective surfaces R2a and R2b at the bonding surface 32a in Figure 14(b), and is incident on the corresponding second lens 22c as shown in Figure 14(a).

[0119] At this time, light L1c enters the second lens 22c in a direction of propagation that is slightly inclined in the X-axis direction relative to the Z-axis direction. However, since the second lens 22c is tilted around the Y-axis as described above, the optical axis of light L1c after passing through the second lens 22c is corrected to be parallel to the Z-axis. This optical axis aligns with the optical axis of the corresponding core 51c. In this way, light L1c is focused by the second lens 22c towards the center of the core 51c.

[0120] Furthermore, at the bonding surface 32a, as shown in Figure 14(b), the light L1a and L1b emitted from the light-emitting elements 41a and 41b, respectively, and parallelized by the first lenses 21a and 21b, respectively, are incident on the reflective surfaces R2a and R2b, respectively. These light L1a and L1b are reflected by the reflective surfaces R2a and R2b. Unlike the reflective surfaces R2c and R2d, the reflective surfaces R2a and R2b are not tilted around the Y axis, so the reflection direction of the light L1a and L1b is parallel to the Z axis.

[0121] Subsequently, these light rays L1a and L1b travel through the inside of the light guide member 20 in the negative Z-axis direction and enter the corresponding second lenses 22a and 22b, as shown in Figure 14(a). The optical axes of these second lenses 22a and 22b are parallel to the Z-axis and are aligned with the optical axes of the incident light rays L1a and L1b. The optical axes of the second lenses 22a and 22b are also aligned with the optical axes of the corresponding cores 51a and 51b. In this way, the light rays L1a and L1b are focused by the second lenses 22a and 22b towards the center of the cores 51a and 51b.

[0122] In the configuration of Embodiment 2, the intensity distribution of light L1a and L1b at the incident end faces of cores 51a and 51b is a nearly identical Gaussian distribution over the entire circumference, similar to Figures 8(a) to (c). The intensity distribution of light L1c and L1d at the incident end faces of cores 51c and 51d is also similar to Figures 8(a) to (c), although it deviates slightly from the Gaussian distribution, it is still close to the Gaussian distribution.

[0123] Therefore, with the configuration of Embodiment 2, as with Embodiment 1, it is possible to transmit a large-capacity optical signal through four transmission systems while suppressing the loss of optical signals.

[0124] In Embodiment 2, as in the modified example 1 above, four light-receiving elements 42a to 42d may be arranged on the substrate 40 in place of four light-emitting elements 41a to 41d. This allows for the configuration of an optical connector 2 for receiving optical signals from cores 51a to 51d.

[0125] <Effects of Embodiment 2> The same effects as those of Embodiment 1 can be achieved with the configuration of Embodiment 2.

[0126] In other words, as shown in Figures 12-14, the optical system 1 comprises: reflective surfaces R2c and R2d (first and second reflective surfaces) arranged at a predetermined angle with respect to a first plane P1 and a second plane P2 that are substantially orthogonal to each other, and arranged sequentially at a predetermined interval in a first direction (positive Z-axis direction) away from the second plane P2; two first lenses 21c and 21d, respectively, arranged between the first plane P1 and the reflective surfaces R2c and R2d (first and second reflective surfaces), forming first focal points F1c and F1d on the first plane P1 side; and two second lenses 22c and 22d, positioned on the second plane P2 side of the reflective surface R2c (first reflective surface), arranged at a predetermined interval in a second direction (X-axis direction), forming second focal points F2c and F2d on the second plane P2 side. The end faces of two optical transmission cores 51c and 51d are positioned at two second focal points F2c and F2d, respectively, and two light-emitting elements 41c and 41d are positioned at two first focal points F1c and F1d, respectively. In the first direction, an optical path (first optical path) of optical light L1c for the transmission of an optical signal via a reflective surface R2c (first reflective surface) is formed between the front first lens 21c and one of the two second lenses 22c and 22d (second lens 22c), and in the first direction, an optical path (second optical path) of optical light L1d for the transmission of the optical signal via a reflective surface R2d (second reflective surface) is formed between the rear first lens 21d and the other of the two second lenses 22c and 22d (second lens 22d), respectively. The reflective surface R2c (first reflective surface) is positioned in a region that does not interfere with the optical path (second optical path) of optical light L1d.

[0127] This configuration allows for a reduction in the width of the substrate 40 in the second direction (X-axis direction), and increases the number of optical systems 1 and optical connectors 2 that can be arranged in a fixed area.

[0128] Furthermore, as shown in Figures 12-14, the optical system 1 includes two other first lenses 21a and 21b positioned at a predetermined distance from the two first lenses 21c and 21d in a direction parallel to the first direction (Z-axis direction), two other second lenses 22a and 22b positioned at a predetermined distance from the two second lenses 22c and 22d in a third direction (Y-axis direction), and one of the two other first lenses 21a and 21b that is closer in the first direction The device comprises a reflective surface R2a (third reflective surface) that forms an optical path (third optical path) of light L1a between the first lens 21a and one of the two other second lenses 22a, 22b (second lens 22a), and a reflective surface R2b (fourth reflective surface) that forms an optical path (fourth optical path) of light L1b between the other first lens 21b that is further back in the first direction and the other of the two other second lenses 22a, 22b (second lens 22b). The end faces of two other cores 51a, 51b for optical transmission are positioned at the second focal points F2a, F2b of the two other second lenses 22a, 22b, respectively, and two other light-emitting elements 41a, 41b are positioned at the first focal points F1a, F1b of the two other first lenses 21a, 21b, respectively. Among the reflective surfaces R2c, R2d, R2a, and R2b (the first to fourth reflective surfaces), the reflective surface that is closer to the front in the first direction than the other reflective surfaces is positioned in a region of the optical paths L1a to L1d (the first to fourth optical paths) that does not interfere with the optical paths formed by the other reflective surfaces.

[0129] With this configuration, the two other light-emitting elements 41a and 41b are also arranged at a predetermined interval in the first direction, so that the width of the substrate 40 on which these light-emitting elements 41a to 41d are mounted does not increase in the second direction. In addition, since optical signals can be further transmitted through the optical paths L1a and L1b (third and fourth optical paths), the speed and capacity of data transmission can be further increased.

[0130] As shown in Figure 12, the other second focal points F2a and F2b of the two other second lenses 22a and 22b are aligned in the third direction (Y-axis direction), and the line connecting the two other second focal points F2a and F2b lies between the second focal points F2c and F2d of the two second lenses 22c and 22d.

[0131] This configuration allows for smooth handling of multicore fibers having four cores 51a to 51d.

[0132] <Embodiment 3> In Embodiment 3, the first lenses 21b and 21d correspond to the "two first lenses" described in the claims, the second lenses 22c and 22d correspond to the "two second lenses" described in the claims, and the reflective surfaces R3b and R3d correspond to the "first and second reflective surfaces" described in the claims, respectively. Furthermore, in Embodiment 3, the first lenses 21a and 21c correspond to the "two other first lenses" described in the claims, the second lenses 22a and 22b correspond to the "two other second lenses" described in the claims, and the reflective surfaces R3a and R3c correspond to the "third reflective surface" and "fourth reflective surface" described in the claims, respectively.

[0133] Figure 15 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to Embodiment 3.

[0134] Similar to Figure 6, Figure 15 also shows a cross-sectional view of the optical connector 2 when it has only one optical system 1.

[0135] Compared to Embodiment 1 described above, Embodiment 3 has a modified arrangement of reflective surfaces that reflect the light L1a to L1d emitted from the light-emitting elements 41a to 41c, respectively. Specifically, the light L1a to L1d emitted from the light-emitting elements 41a to 41c are reflected by reflective surfaces arranged on the four bonding surfaces 33a to 33d, respectively.

[0136] Furthermore, compared to Embodiment 1, Embodiment 3 has modified second lenses and cores to which the light L1a to L1d emitted from the light-emitting elements 41a to 41c are guided. Specifically, light L1a is guided to the second lens 22a and core 51a, light L1b is guided to the second lens 22c and core 51c, light L1c is guided to the second lens 22b and core 51b, and light L1d is guided to the second lens 22d and core 51d.

[0137] Figure 16 is a schematic perspective view showing the configuration of the light guide member 20 according to Embodiment 3.

[0138] The light guide member 20 is composed of five parts 20a to 20e. The parts 20a to 20e are joined together to form a rectangular parallelepiped light guide member 20. Joining surfaces 33a to 33d are formed between adjacent parts. The inclination angle θ1 of the joining surfaces 33a to 33d with respect to the XZ plane is 45°, as in the first embodiment described above.

[0139] The second lenses 22a to 22d are positioned on the negative Z-axis side of part 20a. The layout of the second lenses 22a to 22d is the same as in Figure 13. The second lenses 22a to 22d face the cores 51a to 51d, respectively. The first lenses 21a to 21d are positioned on the upper surfaces of parts 20a to 20d, respectively. Similar to Embodiment 2 described above, the first lenses 21a to 21d are aligned in the Z-axis direction at an intermediate position in the X-axis direction of the light guide member 20.

[0140] A reflective surface R3a is positioned in the lower range of the bonding surface 33a, reflective surfaces R3b and R3d are positioned in the center of the bonding surfaces 33b and 33d, respectively, and a reflective surface R3a is positioned in the upper range of the bonding surface 33d. Reflective surfaces R3a and R3c are perpendicular to the YZ plane. Reflective surface R3b is tilted a few degrees around the Y axis from a state perpendicular to the YZ plane so as to face the second lens 22c, and reflective surface R3d is tilted a few degrees around the Y axis from a state perpendicular to the YZ plane so as to face the second lens 22d.

[0141] The reflective surfaces R3a to R3d are, for example, positioned on the positive Z-axis side (inclined surface) of parts 20a to 20d. The method for positioning the reflective surfaces R3a to R3d on the corresponding sides is the same as in embodiments 1 and 2 described above. That is, steps corresponding to the thickness of the reflective surfaces R3a to R3d are provided on the corresponding sides, and a highly reflective metal material is deposited onto these steps to form the reflective surfaces R3a to R3d. The depth of the steps on which the reflective surfaces R3b and R3d are formed is adjusted so that these reflective surfaces R3b and R3d are inclined by several degrees around the Y-axis as described above.

[0142] Similar to Embodiment 2 described above, the optical axes of the second lenses 22a and 22b are parallel to the Z-axis, while the optical axes of the second lenses 22c and 22d are tilted from being parallel to the Z-axis to being parallel to the XZ plane.

[0143] The optical axes of the first lenses 21a and 21c are bent in the X-axis direction by the reflective surfaces R3a and R3c, respectively, leading to the second lenses 22a and 22b, and aligning with the optical axes of these second lenses 22a and 22b and the cores 51a and 51b, respectively. The optical axis of the first lens 21b is bent by the reflective surface R3b in a direction tilted a few degrees around the Y-axis with respect to the X-axis direction, leading to the second lens 22c, and further bent by the second lens 22c to align with the optical axis of the core 51c. The optical axis of the first lens 21d is bent by the reflective surface R3d in a direction tilted a few degrees around the Y-axis with respect to the X-axis direction, leading to the second lens 22d, and further bent by the second lens 22d to align with the optical axis of the core 51d.

[0144] The materials constituting parts 20a to 20e are the same as those used for parts 20a to 20c in Embodiment 1. Furthermore, the method for forming the first lenses 21a to 21d and the second lenses 22a to 22d on each part is also the same as in Embodiment 1.

[0145] Figures 17(a) to (e) schematically show how light L1a to L1d propagates inside the light guide member 20.

[0146] Figure 17(a) shows the incident state of light L1a to L1d on the second lenses 22a to 22d, and Figures 17(b) to (e) show the incident state of light L1a to L1d on the bonding surfaces 33a to 33d. Figures 17(a) to (e) show the state of light L1a to L1d when the second lenses 22a to 22d and the bonding surfaces 33a to 33e are viewed in the positive Z-axis direction.

[0147] As shown in Figure 17(e), at the bonding surface 33d, light L1d emitted from the light-emitting element 41d and parallelized by the first lens 21d is incident on the reflective surface R3d. The light L1d is reflected by the reflective surface R3d. At this time, the reflection direction of the light L1d is tilted by a few degrees from the negative Z-axis direction to the positive X-axis direction, as shown by the dashed arrow, due to the inclination of the reflective surface R3d around the Y-axis.

[0148] As shown in Figure 17(d), the light L1d reflected by the reflective surface R3d passes through the region on the negative Y-axis side of the reflective surface R3c where there is no reflective surface at the bonding surface 33c, and proceeds to the bonding surface 33b. As described above, the direction of propagation of the light L1d has a component in the positive X-axis direction, so at the position of the bonding surface 33b in Figure 17(c), the light L1d passes through the region on the positive X-axis side of the reflective surface R3b where there is no reflective surface, and proceeds to the bonding surface 33a. As shown in Figure 17(b), at the bonding surface 33a, the light L1d passes through the region on the positive Y-axis side of the reflective surface R3a where there is no reflective surface, and proceeds through the inside of the light guide member 20 in the same direction of propagation, and as shown in Figure 17(a), it is incident on the corresponding second lens 22d.

[0149] At this time, light L1d enters the second lens 22d with a direction of propagation that is slightly inclined in the X-axis direction relative to the Z-axis direction. However, as described above, the second lens 22d is tilted around the Y-axis, so the optical axis of light L1d after passing through the second lens 22d is corrected to be parallel to the Z-axis. This optical axis aligns with the optical axis of the corresponding core 51d. In this way, light L1d is focused by the second lens 22d towards the center of the core 51d.

[0150] As shown in Figure 17(d), at the bonding surface 33c, light L1c emitted from the light-emitting element 41c and parallelized by the first lens 21c is incident on the reflective surface R3c. Light L1c is reflected in the positive Z-axis direction by the reflective surface R3c. Subsequently, light L1c passes through the regions of the bonding surfaces 33b and 33a where there are no reflective surfaces R3b and R3a, and is incident on the second lens 22b. The optical axis of the second lens 22b is parallel to the Z-axis and is aligned with the optical axis of the incident light L1c. The optical axis of the second lens 22b is also aligned with the optical axis of the corresponding core 51b. In this way, light L1c is focused by the second lens 22b towards the center of the core 51b.

[0151] As shown in Figure 17(c), at the bonding surface 33b, light L1b emitted from the light-emitting element 41b and parallelized by the first lens 21b is incident on the reflective surface R3b. The direction of reflection of light L1b by the reflective surface R3b is tilted a few degrees from the negative Z-axis direction to the negative X-axis direction, as shown by the dashed arrow, due to the tilt of the reflective surface R3b around the Y-axis. Subsequently, as shown in Figure 17(b), light L1b passes through the region without the reflective surface R3a at the bonding surface 33a and is incident on the second lens 22c.

[0152] As described above, the second lens 22c is tilted around the Y-axis, so the optical axis of the light L1b after passing through the second lens 22c is corrected to be parallel to the Z-axis. This optical axis aligns with the optical axis of the corresponding core 51c. In this way, the light L1b is focused by the second lens 22c towards the center of the core 51c.

[0153] As shown in Figure 17(b), at the bonding surface 33a, light L1a emitted from the light-emitting element 41a and parallelized by the first lens 21a is incident on the reflective surface R3a. Since the reflective surface R3a is not tilted around the Y-axis, the direction of reflection of light L1a by the reflective surface R3a is positive along the Z-axis. Subsequently, light L1a is incident on the second lens 22a. Since the second lens 22a is not tilted around the Y-axis, the optical axis of the second lens 22a is aligned with the optical axis of the incident light L1a. Furthermore, the optical axis of the second lens 22a is also aligned with the optical axis of the corresponding core 51a. In this way, light L1a is focused by the second lens 22a towards the center of the core 51a.

[0154] In the configuration of Embodiment 3, the intensity distribution of light L1a and L1c at the incident end faces of cores 51a and 51b is a nearly identical Gaussian distribution over the entire circumference, similar to Figures 8(a) to (c). The intensity distribution of light L1b and L1d at the incident end faces of cores 51c and 51d is similar to Figures 8(a) to (c), although it deviates slightly from the Gaussian distribution, it is still close to the Gaussian distribution.

[0155] Therefore, with the configuration of Embodiment 3, similar to Embodiments 1 and 2, it is possible to transmit a large amount of optical signal through four transmission systems while suppressing the loss of optical signals.

[0156] In Embodiment 3, as in the modified example 1 above, four light-receiving elements 42a to 42d may be arranged on the substrate 40 in place of four light-emitting elements 41a to 41d. This allows for the configuration of an optical connector 2 for receiving optical signals from the cores 51a to 51d.

[0157] <Effects of Embodiment 3> Embodiment 3 also achieves the same effects as Embodiment 2.

[0158] <Example of changes> The correspondence between the light L1a to L1d emitted from the light-emitting elements 41a to 41d and the cores 51a to 51d is not limited to the correspondence in the above embodiment 3, but can be changed as appropriate.

[0159] For example, as shown in Figures 18 and 19(a) to (e), the arrangement and inclination of the reflective surfaces R3a to R3d on the bonding surfaces 33a to 33d may be adjusted so that light L1a to L1d is incident on the second lenses 22d, 22c, 22a, and 22b respectively and focused on the cores 51d, 51c, 51a, and 51b, respectively.

[0160] In the configurations shown in Figures 18 and 19, light rays L1d and L1c are reflected by the reflective surfaces R3d and R3c, respectively, and travel in the negative Z-axis direction, entering the second lenses 22b and 22a, respectively. Light ray L1b is reflected by the reflective surface R3b and travels in a direction tilted by a few degrees in the negative X-axis direction relative to the negative Z-axis direction, entering the second lens 22c. Light ray L1a is reflected by the reflective surface R3a and travels in a direction tilted by a few degrees in the positive X-axis direction relative to the negative Z-axis direction, entering the second lens 22d. Similar to Embodiment 3 described above, the optical axes of the second lenses 22a and 22b are parallel to the Z-axis, and the optical axes of the second lenses 22c and 22d are tilted around the Y-axis with respect to the Z-axis. As a result, light rays L1a to L1d are focused near the center of the cores 51d, 51c, 51a, and 51b.

[0161] This modified example can also achieve the same effects as Embodiment 3 described above.

[0162] In this modified example, the first lenses 21a and 21b correspond to the "two first lenses" described in the claims, the second lenses 22d and 22c correspond to the "two second lenses" described in the claims, and the reflective surfaces R3a and R3b correspond to the "first and second reflective surfaces" described in the claims, respectively. Furthermore, in this modified example, the first lenses 21c and 21d correspond to the "two other first lenses" described in the claims, the second lenses 22a and 22b correspond to the "two other second lenses" described in the claims, and the reflective surfaces R3c and R3d correspond to the "third reflective surface" and "fourth reflective surface" described in the claims, respectively.

[0163] <Embodiment 4> Figure 20 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to Embodiment 4.

[0164] Similar to Figure 6, Figure 20 also shows a cross-sectional view of the optical connector 2 when the optical connector 2 has only one optical system 1.

[0165] In Embodiment 1 described above, the reflective surfaces R1c and R1d were tilted around the Y-axis in order to cause the light rays L1c and L1d to enter the second lenses 22c and 22d. In contrast, in Embodiment 4, without tilting the reflective surfaces R1c and R1d around the Y-axis, the optical axes of the first lenses 21c and 21d are tilted around the Z-axis from a state parallel to the Y-axis to cause the light rays L1c and L1d to enter the second lenses 22c and 22d.

[0166] The first lenses 21c and 21d are tilted around the Z axis such that the direction of propagation of the light L1c and L1d that passes through them and is made into parallel light is tilted by a few degrees in the negative X-axis direction with respect to the negative Y-axis direction. As a result, the direction of propagation of the light L1c and L1d reflected by the reflective surfaces R1c and R1d, respectively, has a component in the negative X-axis direction with respect to the negative Z-axis direction. As a result, the light L1c and L1d are incident on the second lenses 22c and 22d, respectively. In other words, the first lenses 21c and 21d are tilted around the Z axis such that the light L1c and L1d are incident on the vicinity of the center of the second lenses 22c and 22d, respectively. Similar to Embodiment 1 above, the second lenses 22c and 22d are tilted around the Y axis such that the light L1c and L1d are focused on the vicinity of the center of the cores 51c and 51d.

[0167] In Embodiment 4, since the reflective surfaces R1c and R1d cannot be individually tilted around the Y-axis, they may be part of a single reflective surface perpendicular to the YZ plane, similar to the reflective surface R0.

[0168] Furthermore, in the configuration shown in Figure 20, the first lenses 21c and 21d are tilted around the Z-axis to introduce a negative X-axis component into the direction of light L1c and L1d's propagation. However, instead of tilting the first lenses 21c and 21d around the Z-axis, the optical axes of the first lenses 21c and 21d are shifted in the positive X-axis direction relative to the optical axes of the light-emitting elements 41c and 41d, thereby introducing a negative X-axis component into the direction of light L1c and L1d's propagation.

[0169] In Embodiment 4, as in the modified example 1 above, four light-receiving elements 42a to 42d may be arranged on the substrate 40 in place of four light-emitting elements 41a to 41d. This allows for the configuration of an optical connector 2 for receiving optical signals from the cores 51a to 51d.

[0170] Furthermore, in embodiments 2 and 3 described above, instead of tilting the corresponding reflective surface around the Y axis, the corresponding first lens may be tilted around the Z axis or the corresponding first lens may be eccentric in the X-axis direction to give the corresponding light a component in the X-axis direction in the propagation direction of the light, and these lights may be incident on the corresponding second lens.

[0171] <Effects of Embodiment 4> The same effects as those of Embodiment 1 can be achieved with the configuration of Embodiment 4.

[0172] Furthermore, in the configuration of Embodiment 4, as in the case of Figure 4, when viewed in the first direction, the reflective surface R1a (first reflective surface) and the reflective surface R1c (second reflective surface) overlap in at least a portion. As described above, the tilt around the Z axis is adjusted with respect to the first lens 21c on the far side in the first direction, and as in the case of Figure 7(b), the optical path of light L1c (second optical path) passes outside the reflective surface R1a (first reflective surface).

[0173] With this configuration, by adjusting the tilt of the first lens 21c on the rear side, interference of the optical path (second optical path) of light L1c with respect to the reflective surface R1a (first reflective surface) can be avoided.

[0174] <Embodiment 5> Figure 21 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to Embodiment 5.

[0175] Similar to Figure 6, Figure 21 also shows a cross-sectional view of the optical connector 2 when the optical connector 2 has only one optical system 1.

[0176] Compared to Embodiment 1 described above, in Embodiment 5, the inclination angle θ2 of the bonding surfaces 31a and 31b (reflecting surfaces R0, R1c, and R1d) with respect to the XZ plane is changed to 35°. Accordingly, in Embodiment 5, the arrangement of the four first lenses 21a to 21d is changed from the arrangement shown in Figure 6.

[0177] In other words, the direction of propagation of light L1a to L1d before it enters these reflective surfaces is tilted by a few degrees in the negative Z-axis direction with respect to the negative Y-axis direction, so that the optical paths of light L1a to L1d after reflection from the reflective surfaces R0 (R1a, R1b) and R1c, R1d are parallel to the XZ plane. For this purpose, the first lenses 21a to 21d are arranged such that their respective optical axes are offset in the negative Z-axis direction with respect to the optical axes of the light-emitting elements 41a to 41d. Alternatively, instead of arranging the first lenses 21a to 21d eccentrically in this way, the direction of propagation of light L1a to L1d may be tilted by a few degrees in the negative Z-axis direction with respect to the negative Y-axis direction by tilting the optical axes of the first lenses 21a to 21d around the X-axis from a state parallel to the Y-axis.

[0178] The reflective surfaces R1c and R1d are positioned to cover the incident regions of light L1c and L1d, respectively. The configuration of the optical connector 2, other than that described above, is the same as that in Figure 6. The method for forming the reflective surfaces R0, R1c, and R1d is also the same as in Figure 6. The inclination angle θ2 can be substantially 35°.

[0179] <Effects of Embodiment 5> In the configuration of Embodiment 5, the first lenses 21a to 21d are arranged eccentrically with respect to the optical axis of the light-emitting elements 41a to 41d, or tilted around the X-axis, as described above. As a result, the intensity of light L1a to L1d at the incident end faces of the cores 51a to 51d is slightly deviated from the Gaussian distribution. Therefore, compared to Embodiment 1, the optical coupling efficiency between light L1a to L1d and the cores 51a to 51d is slightly reduced, and some optical loss may occur when light L1a to L1d is incident from the optical system 1 to the cores 51a to 51d.

[0180] However, even in the configuration shown in Figure 21 according to Embodiment 5, since the light-emitting elements 41a to 41d are arranged in the Z-axis direction, the width of the substrate 40 in the X-axis direction can be reduced, and the number of optical systems 1 that can be arranged in a fixed area can be increased.

[0181] In Embodiment 5, as in the modified example 1 above, four light-receiving elements 42a to 42d may be arranged on the substrate 40 in place of four light-emitting elements 41a to 41d. This allows for the configuration of an optical connector 2 for receiving optical signals from the cores 51a to 51d.

[0182] Furthermore, the same configuration as in Embodiment 5 may be applied to the configurations of Embodiments 2 to 4.

[0183] <Effects of Embodiment 5> According to the configuration of Embodiment 5, although the utilization efficiency of light L1a to L1d is slightly reduced as described above, the same effects as those of Embodiment 1 can be generally achieved.

[0184] Furthermore, when the light guide member 20 is made of light-transmitting silicon, the accuracy of the inclination and height of the joint surfaces 31a and 31b (inclined surfaces) of the light guide member 20 on which the reflective surfaces R1a to R1d are arranged can be maximized when these joint surfaces 31a and 31b (inclined surfaces) are substantially inclined at 35° with respect to the first plane P1, due to the relationship with the crystal orientation of silicon. Therefore, according to the configuration of Embodiment 5, the reflective surfaces R1a to R1d can be accurately arranged with the target inclination and height, and optical signals can be transmitted smoothly.

[0185] <Embodiment 6> Figure 22 is a schematic cross-sectional view showing the configuration of the optical connector 2 according to Embodiment 6.

[0186] Similar to Figure 6, Figure 22 also shows a cross-sectional view of the optical connector 2 when it has only one optical system 1.

[0187] Compared to Embodiment 1 described above, Embodiment 6 has a modified arrangement of the light-emitting elements 41a to 41d. Specifically, in Embodiment 6, the light-emitting elements 41c and 41d are positioned offset from the light-emitting elements 41a and 41b in the negative X-axis direction. The light-emitting elements 41a to 41d are arranged at predetermined intervals in the Z-axis direction. The light-emitting elements 41a and 41b are aligned linearly in the Z-axis direction, and the light-emitting elements 41c and 41d are aligned linearly in the Z-axis direction.

[0188] Along with this change in the arrangement of the light-emitting elements 41a to 41d, the arrangement of the first lenses 21a to 21d has also been changed. The first lenses 21a to 21d are positioned opposite each other to the light-emitting elements 41a to 41d. In addition, along with the change in the arrangement of the light-emitting elements 41a to 41d and the first lenses 21a to 21d, the arrangement areas of the reflective surfaces R1c and R1d have been changed.

[0189] Figure 23 is a schematic perspective view showing the configuration of the light guide member 20 according to Embodiment 6.

[0190] As shown in Figure 23, the first lenses 21c and 21d are positioned between a plane passing through the centers of the second lenses 22a and 22b and parallel to the YZ plane, and a plane passing through the centers of the second lenses 22c and 22d and parallel to the YZ plane. As a result of changing the arrangement of the first lenses 21c and 21d, the reflective surfaces R1c and R1d are widened in the negative Z-axis direction.

[0191] The optical axis of the first lens 21c is bent by the reflective surface R1c in a direction inclined in the negative X-axis direction relative to the negative Z-axis direction, and reaches the center of the second lens 22c. The optical axis of the first lens 21d is bent by the reflective surface R1d in a direction inclined in the negative X-axis direction relative to the negative Z-axis direction, and reaches the center of the second lens 22d. Therefore, the reflective surfaces R1c and R1d are tilted by a few degrees around the Y-axis from a state perpendicular to the YZ plane. The second lenses 22c and 22d slightly bend the optical axes of the first lenses 21c and 21d in the positive X-axis direction to align them with the optical axes of the cores 51c and 51d, respectively. For this purpose, the second lenses 22c and 22d are slightly tilted around the Y-axis. The other configurations of the light guide member 20 are the same as in Embodiment 1 described above.

[0192] Figures 24(a) to (c) schematically show how light L1a to L1d propagates inside the light guide member 20 according to Embodiment 6.

[0193] The basic functions of each reflective surface R0, R1c, and R1d, and the basic behavior of the light L1a to L1d are the same as in Embodiment 1 described above. As shown in Figure 24(c), the incident positions of the light L1c and L1d on the reflective surfaces R1c and R1d are shifted in the negative X-axis direction compared to Figure 7(c), making it easier to redirect the light L1c and L1d to the outside of the reflective surface R0 (the region without the reflective surface R0 on the negative X-axis side) at the junction surface 31a in Figure 24(b).

[0194] In Embodiment 6, as in the modified example 1 above, four light-receiving elements 42a to 42d may be arranged on the substrate 40 in place of four light-emitting elements 41a to 41d. This allows for the configuration of an optical connector 2 for receiving optical signals from the cores 51a to 51d.

[0195] <Effects of Embodiment 6> In the configuration of Embodiment 6, although not all of the light-emitting elements 41a to 41d are aligned in a straight line along the Z-axis, the light-emitting elements 41a to 41d are arranged at predetermined intervals along the Z-axis, and no light-emitting elements are aligned along the X-axis. Therefore, compared to the case where multiple light-emitting elements are arranged in a line along the X-axis, the width of the substrate 40 in the X-axis direction can be reduced, and more optical systems 1 can be arranged in a line along the X-axis direction.

[0196] Furthermore, in the configuration of Embodiment 6, as shown in the upper left of Figure 22, a space S1 is created on the negative X-axis side of the light-emitting elements 41a and 41b, and a space S2 is created on the positive X-axis side of the light-emitting elements 41c and 41d. Therefore, wiring and terminals connected to the light-emitting elements 41a and 41b can be placed in space S1, and wiring and terminals connected to the light-emitting elements 41c and 41d can be placed in space S2. In this way, by utilizing spaces S1 and S2, the width of the substrate 40 on which the wiring and terminals are mounted can be reduced in the X-axis direction. In this case, the layout of the wiring 13 shown in Figure 2 should be changed to a layout that sandwiches the recess 15 in the X-axis direction.

[0197] Furthermore, the same configuration as in Embodiment 6 may be applied to Embodiments 2 to 5 described above.

[0198] <Other examples of changes> In embodiments 1 to 6 described above, single-surface refractive lenses were shown as the first lenses 21a to 21d and the second lenses 22a to 22d, but the first lenses 21a to 21d and the second lenses 22a to 22d may also be Fresnel lenses or diffracting lenses.

[0199] Furthermore, in embodiments 1 to 6 described above, four cores 51a to 51d were arranged in one optical fiber 50. However, the number of cores arranged in the optical fiber 50 is not limited to this, and multiple cores other than four may be arranged in the optical fiber 50. In this case, the number of light-emitting elements, first lenses, and second lenses should be arranged in a number corresponding to the number of cores.

[0200] Furthermore, in the above embodiment 1, two cores 51a and 51b are arranged side by side in the X-axis direction, and two cores 51c and 51d are arranged side by side in the X-axis direction, but three or more cores may be arranged side by side in the X-axis direction. In this case, the number of second lenses arranged in the X-axis direction increases in proportion to the increase in the number of cores arranged in the X-axis direction, and the number of first lenses and light-emitting elements arranged in the X-axis direction also increases. In addition, the number of reflective surfaces also increases in proportion to these increases. The inclination of each reflective surface around the Y-axis is adjusted so as to guide the corresponding light to the corresponding second lens. Furthermore, reflective surfaces on the negative Z-axis side where other reflective surfaces exist should be arranged in a region that includes the incident region of the corresponding light and does not obstruct light from other reflective surfaces (a region that does not interfere with the optical path of light from other reflective surfaces).

[0201] Alternatively, multiple cores may be arranged in a single row in the second direction (X-axis direction). In this case, the same number of second lenses as the number of cores are arranged opposite the corresponding cores, and the same number of first lenses as the number of cores are arranged at predetermined intervals in the first direction (positive Z-axis direction). In addition, multiple reflective surfaces are arranged to guide the optical axis of each first lens to the corresponding second lens. These reflective surfaces should be tilted around an axis parallel to the third direction (Y-axis direction) so that the corresponding optical axis is guided to the corresponding second lens.

[0202] Furthermore, in embodiments 1 to 6 described above, multiple first lenses 21a to 21d and multiple second lenses 22a to 22d were arranged on the upper surface and side surface of the light guide member 20, respectively. However, the method of arranging these first lenses 21a to 21d and second lenses 22a to 22d is not limited to this. For example, the second lenses 22a to 22d may be omitted from the light guide member 20, and a lens array having multiple second lenses 22a to 22d may be arranged on the support member 10 separately from the light guide member 20.

[0203] However, in this case, when installing the light guide member 20 and the lens array, it is necessary to adjust the positional relationship between each of the second lenses 22a to 22d on the lens array, the first lenses 21a to 21d, and the corresponding reflective surface. In contrast, in embodiments 1 to 6 described above, the multiple first lenses 21a to 21d and the multiple second lenses 22a to 22d and the corresponding reflective surfaces are integrated into the light guide member 20 with their positional relationships already adjusted, so such positional adjustment is not necessary. Therefore, in embodiments 1 to 6 described above, the multiple first lenses 21a to 21d, the multiple second lenses 22a to 22d, and their respective reflective surfaces can be installed on the support member 10 more easily and accurately.

[0204] Furthermore, in embodiments 1 to 3 described above, the four first foci F1a to F1d were included in the first plane P1, but the four first foci F1a to F1d do not need to be strictly included in the first plane P1; it is sufficient if they are substantially included in the first plane P1. Similarly, the four second foci F2a to F2d do not need to be substantially included in the second plane P2. The first plane P1 and the second plane P2 do not need to be strictly orthogonal; it is sufficient if they are substantially orthogonal.

[0205] Furthermore, if the light-emitting points of the light-emitting elements 41a to 41d are different from each other in the Y-axis direction, the first focal points F1a to F1d of the first lenses 21a to 21d are not included in the first plane P1, and should be formed at the height of each light-emitting point of the light-emitting elements 41a to 41d. Similarly, if the end faces of the cores 51a to 51d are offset in the Z-axis direction, the second focal points F2a to F2d of the second lenses 22a to 22d are not included in the second plane P2, and should be formed at the positions of each end face of the cores 51a to 51d.

[0206] Furthermore, the configuration of the optical system 1 and the optical connector 2 is not limited to the configurations shown in embodiments 1 to 6 above, and other configurations may be used.

[0207] For example, the range of reflective surfaces that reflect each of the light rays L1a to L1d may be limited to the range of the junction surface to which the corresponding light is incident. For example, in Figure 7(b), reflective surfaces R1a and R1b are formed by a part of the common reflective surface R0, but reflective surfaces R1b and R1a may be placed only in the areas enclosed by the two dashed rectangles in the same figure. Also, in Figure 7(c), the boundaries of reflective surfaces R1c and R1d are touching, but the boundaries of reflective surfaces R1c and R1d may be separated.

[0208] Furthermore, the number of optical systems 1 arranged in the optical connector 2 is not limited to three, but may be one, two, or four or more. Also, among the multiple optical systems 1 arranged in one optical connector 2, a predetermined optical system 1 may be used for data transmission and the remaining optical systems 1 may be used for data reception. In this case, a substrate 40 having a light-emitting element is installed in the optical system 1 for data transmission, and a substrate 40 having a light-receiving element is installed in the optical system 1 for data reception.

[0209] Embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical idea set forth in the claims.

[0210] (Note) The above description of embodiments discloses the following technologies.

[0211] (Technology 1) An optical system for transmitting optical signals, A first and second reflective surface, which are arranged at a predetermined angle with respect to a first and second plane that are substantially orthogonal to each other, and which are arranged sequentially at a predetermined interval in a first direction away from the second plane, Two first lenses are positioned between the first plane and the first and second reflective surfaces, respectively, and each forms a first focal point on the first plane side. The system comprises two second lenses positioned on the second plane side of the first reflective surface, arranged at a predetermined interval in a second direction parallel to the first plane and perpendicular to the first direction, each forming a second focal point on the second plane side, The end faces of two cores for optical transmission are positioned at the two aforementioned second focal points, Two light-emitting elements or two light-receiving elements are positioned at the two aforementioned first focal points, In the first direction, a first optical path for transmitting the optical signal via the first reflective surface is formed between the first lens in the foreground and one of the two second lenses. In the first direction, a second optical path for transmitting the optical signal via the second reflective surface is formed between the rearmost first lens and the other of the two second lenses. The first reflective surface is positioned in a region that does not interfere with the second optical path. An optical system characterized by the following features.

[0212] According to this technology, since two light-emitting elements or two photodetectors are arranged at a predetermined interval in the first direction, the width of the substrate on which these elements are mounted in the second direction can be reduced. Therefore, the number of optical systems that can be arranged side by side in the second direction for a given area can be increased, resulting in faster and larger data transmission capacity.

[0213] (Technology 2) In the optical system described in Technical 1, When viewed in the first direction, the first reflective surface and the second reflective surface overlap in at least a portion of the same area. The inclination of the second reflecting surface around an axis perpendicular to both the first and second directions is adjusted so that the second optical path passes outside the first reflecting surface. An optical system characterized by the following features.

[0214] This technology allows for avoiding interference of the second optical path with respect to the first reflective surface by adjusting the inclination of the second reflective surface.

[0215] (Technology 3) In the optical system described in Technology 1 or 2, When viewed in the first direction, the first reflective surface and the second reflective surface overlap in at least a portion of the same area. In the first direction, the inclination of the first lens on the rear side is adjusted around an axis parallel to the first direction so that the second optical path passes outside the first reflective surface. An optical system characterized by the following features.

[0216] According to this technology, interference of the second optical path with respect to the first reflective surface can be avoided by adjusting the tilt of the first lens at the rear.

[0217] (Technology 4)1~3 In the optical system described in any of Technology 1 to 3, Two other first lenses are arranged at a predetermined distance from the two first lenses in a direction parallel to the first direction, Two other second lenses are arranged at a predetermined distance from the two aforementioned second lenses in a third direction perpendicular to both the first and second directions, A third reflective surface that forms a third optical path between the other first lens that is closer in the first direction and one of the two other second lenses, The device further comprises a fourth reflective surface that forms a fourth optical path between the other first lens, which is the innermost of the two other first lenses in the first direction, and the other of the two other second lenses, The end faces of the two other cores for optical transmission are positioned at the second focal points of the two other second lenses, respectively. Two other light-emitting elements or two other light-receiving elements are positioned at the first focal points of the two other first lenses, respectively. The reflective surface among the first to fourth reflective surfaces that is closer to the front in the first direction than the other reflective surfaces is located in a region of the first to fourth optical paths that does not interfere with the optical paths formed by the other reflective surfaces. An optical system characterized by the following features.

[0218] According to this technology, since two other light-emitting elements or two other photodetectors are also arranged at predetermined intervals in the first direction, it is possible to suppress an increase in the width of the substrate in the second direction on which these elements are mounted. Furthermore, since optical signals can be transmitted further through the third and fourth optical paths, it is possible to further increase the speed and capacity of data transmission.

[0219] (Technology 5) In the optical system described in Technical 4, The other second focal points of the two other second lenses are aligned in the third direction with respect to the second focal points of the two second lenses. An optical system characterized by the following features.

[0220] This technology allows for smooth handling of multi-core fibers with four cores.

[0221] (Technology 6) In the optical system described in Technical 4, The other second focal points of the two other second lenses are aligned in the third direction, and the line connecting the two other second focal points lies between the second focal points of the two second lenses. An optical system characterized by the following features.

[0222] This technology allows for smooth handling of multi-core fibers with four cores.

[0223] (Technology 7) In the optical system described in any of Technical 4 to 6, Of the first to fourth reflective surfaces, the two reflective surfaces from the front in the first direction are part of a common reflective surface that extends in a single plane. An optical system characterized by the following features.

[0224] This technology allows for a simplification of the optical system configuration.

[0225] (Technology 8) In the optical system described in any of Technical 4 to 7, The two first lenses and the two other first lenses are arranged substantially in a straight line in the first direction. An optical system characterized by the following features.

[0226] This technology allows for an effective reduction in the substrate width in the second direction. Furthermore, when light-emitting elements are positioned at two first foci and two other first foci, a linear array of light-emitting elements can be used.

[0227] (Technology 9) In the optical system described in any of Technology 1 to 8, The two first foci are each formed on the first plane, The two second foci are formed on the second plane, An optical system characterized by the following features.

[0228] According to this technology, since it is only necessary to arrange two light-emitting elements or two photodetectors on a first plane, if these light-emitting elements or photodetectors are of the same type, or if their height (thickness) is the same, they can simply be mounted and arranged on a flat substrate. Furthermore, since the end faces of the two cores can both be arranged on a second plane, for example, when the end faces of multiple cores, such as in a multicore fiber, are already included in the same plane, the end faces of these cores can be easily positioned at their respective second focal points.

[0229] (Technology 10) In the optical system described in any of Technology 1 to 9, The first and second reflective surfaces, the two first lenses, and the two second lenses are integrally arranged on the light guide member. An optical system characterized by the following features.

[0230] This technology allows for the fixing of the positional relationship between the first and second reflective surfaces, the two first lenses, and the two second lenses, thereby suppressing the loss of optical signals due to misalignment between these reflective surfaces and lenses. Furthermore, by installing the light guide member on the support member, these reflective surfaces and lenses can be installed on the support member, simplifying the installation process for these reflective surfaces and lenses on the support member.

[0231] (Technology 11) In the optical system described in any of Technology 1 to 10, The first and second reflective surfaces are inclined at a substantially 45° angle with respect to the first and second planes, The portions of the first and second optical paths between the first and second reflective surfaces and the two second lenses are parallel to the first plane. An optical system characterized by the following features.

[0232] According to this technology, when light-emitting elements with a Gaussian emission intensity distribution are positioned at each first focal point, the light intensity at the incident end face of each core can be made to approximate a Gaussian distribution. This increases the coupling efficiency of light to each single-mode core and effectively suppresses optical signal loss.

[0233] (Technology 12) In the optical system described in any of Technology 1 to 10, The first and second reflective surfaces are arranged on the light guide member. The first and second reflective surfaces are inclined at a substantially 35° angle with respect to the first plane. The portions of the first and second optical paths between the first and second reflective surfaces and the two second lenses are parallel to the first plane. An optical system characterized by the following features.

[0234] According to this technology, when the light guide member is made of light-transmitting silicon, the accuracy of the inclination and height of the inclined surface of the light guide member on which the reflective surface is located can be maximized when the inclined surface is substantially tilted at 35° with respect to the first plane, due to the relationship with the crystal orientation of the silicon. Therefore, with this configuration, the first and second reflective surfaces can be precisely positioned at the target inclination and height, and optical signals can be transmitted smoothly.

[0235] (Technology 13) An optical system described in any one of the technical items 1 through 12, At least one optical fiber constituting a core located at the two second focal points, A light-emitting element or light-receiving element is positioned at each of the two first focal points, The optical system comprises the optical fiber and a support member that supports the light-emitting element or the light-receiving element. An optical connector characterized by the following features.

[0236] According to the optical connector of this technology, since an optical system according to any of technologies 1 to 11 is used, the same effects as those of technologies 1 to 11 can be achieved.

[0237] (Technology 14) In the optical connector described in Technical 13, The optical fiber is a multicore fiber having the plurality of cores. An optical connector characterized by the following features.

[0238] According to this technology, by installing a single optical fiber in a support member, multiple cores for transmitting optical signals can be arranged, and the end faces of these cores can be positioned at their respective second focal points.

[0239] (Technology 15) In the optical connector described in Technical 13 or 14, Each of the aforementioned plurality of light-emitting elements is a surface-emitting laser. An optical connector characterized by the following features.

[0240] According to this technology, by using a surface-emitting laser with a small emission angle as a light-emitting element, the beam diameter of the light incident on the first lens can be reduced. As a result, the effective diameter of each first lens can be reduced, and consequently, an increase in the size of the optical system and the optical connector in the first direction can be suppressed.

[0241] (Technology 16) In the optical connector according to any one of Technologies 13 to 15, the wavelength of the light emitted from the plurality of light-emitting elements is included in the range of 850 nm or more and 1550 nm or less, an optical connector characterized by this.

[0242] According to this technology, an optical signal can be smoothly transmitted while suppressing the loss of the optical signal.

Explanation of Signs

[0243] 1 Optical system 2 Optical connector 10 Support member 20 Light guide member 21a to 21d First lens 22a to 22d Second lens R1a to R1d, R2a to R2d, R3a to R3d Reflecting surface 40 Substrate 41a to 41d Light-emitting element 42a to 42d Light-receiving element 50 Optical fiber 51a to 51d Core F1a to F1d First focal point F2a to F2d Second focal point L1a to L1d Light P1 First plane P2 Second plane

Claims

1. An optical system for transmitting optical signals, A first and second reflective surface, which are arranged at a predetermined angle with respect to a first and second plane that are substantially orthogonal to each other, and which are arranged sequentially at a predetermined interval in a first direction away from the second plane, Two first lenses are positioned between the first plane and the first and second reflective surfaces, respectively, and each forms a first focal point on the first plane side. The system comprises two second lenses positioned on the second plane side of the first reflective surface, arranged at a predetermined interval in a second direction parallel to the first plane and perpendicular to the first direction, each forming a second focal point on the second plane side, The end faces of two cores for optical transmission are positioned at the two aforementioned second focal points, Two light-emitting elements or two light-receiving elements are positioned at the two aforementioned first focal points, In the first direction, a first optical path for transmitting the optical signal via the first reflective surface is formed between the first lens in the foreground and one of the two second lenses. In the first direction, a second optical path for transmitting the optical signal via the second reflective surface is formed between the rearmost first lens and the other of the two second lenses. The first reflective surface is positioned in a region that does not interfere with the second optical path. An optical system characterized by the following features.

2. In the optical system according to claim 1, When viewed in the first direction, the first reflective surface and the second reflective surface overlap in at least a portion of the same area. The inclination of the second reflecting surface around an axis perpendicular to both the first and second directions is adjusted so that the second optical path passes outside the first reflecting surface. An optical system characterized by the following features.

3. In the optical system according to claim 1, When viewed in the first direction, the first reflective surface and the second reflective surface overlap in at least a portion of the same area. In the first direction, the inclination of the first lens on the rear side is adjusted around an axis parallel to the first direction so that the second optical path passes outside the first reflective surface. An optical system characterized by the following features.

4. In the optical system according to claim 1, Two other first lenses are arranged at a predetermined distance from the two first lenses in a direction parallel to the first direction, Two other second lenses are arranged at a predetermined distance from the two aforementioned second lenses in a third direction perpendicular to both the first and second directions, A third reflective surface that forms a third optical path between the other first lens that is closer in the first direction and one of the two other second lenses, The device further comprises a fourth reflective surface that forms a fourth optical path between the other first lens, which is the innermost of the two other first lenses in the first direction, and the other of the two other second lenses, The end faces of two other cores for optical transmission are positioned at the second focal points of the two other second lenses, respectively. Two other light-emitting elements or two other light-receiving elements are positioned at the first focal points of the two other first lenses, respectively. The reflective surface among the first to fourth reflective surfaces that is closer to the front in the first direction than the other reflective surfaces is positioned in a region of the first to fourth optical paths that does not interfere with the optical paths formed by the other reflective surfaces. An optical system characterized by the following features.

5. In the optical system according to claim 4, The other second focal points of the two other second lenses are aligned in the third direction with respect to the second focal points of the two second lenses. An optical system characterized by the following features.

6. In the optical system according to claim 4, The other second focal points of the two other second lenses are aligned in the third direction, and the line connecting the two other second focal points lies between the second focal points of the two second lenses. An optical system characterized by the following features.

7. In the optical system according to claim 4, Of the first to fourth reflective surfaces, the two reflective surfaces from the front in the first direction are part of a common reflective surface that extends in a single plane. An optical system characterized by the following features.

8. In the optical system according to claim 4, The two first lenses and the two other first lenses are arranged substantially in a straight line in the first direction. An optical system characterized by the following features.

9. In the optical system according to claim 1, The two first foci are each formed on the first plane, The two second foci are each formed on the second plane, An optical system characterized by the following features.

10. In the optical system according to claim 1, The first and second reflective surfaces, the two first lenses, and the two second lenses are integrally arranged on the light guide member. An optical system characterized by the following features.

11. In the optical system according to claim 1, The first and second reflective surfaces are inclined at a substantially 45° angle with respect to the first and second planes, The portions of the first and second optical paths between the first and second reflective surfaces and the two second lenses are parallel to the first plane. An optical system characterized by the following features.

12. In the optical system according to claim 5, The first and second reflective surfaces are arranged on the light guide member. The first and second reflective surfaces are inclined at a substantially 35° angle with respect to the first plane. The portions of the first and second optical paths between the first and second reflective surfaces and the two second lenses are parallel to the first plane. An optical system characterized by the following features.

13. An optical system according to any one of claims 1 to 12, At least one optical fiber constituting a core located at the two second focal points, A light-emitting element or light-receiving element is arranged at each of the two first focal points, The optical system comprises the optical fiber and a support member that supports the light-emitting element or the light-receiving element. An optical connector characterized by the following features.

14. In the optical connector according to claim 13, The optical fiber is a multicore fiber having the plurality of cores. An optical connector characterized by the following features.

15. In the optical connector according to claim 13, Each of the aforementioned plurality of light-emitting elements is a surface-emitting laser. An optical connector characterized by the following features.

16. In the optical connector according to claim 13, The wavelength of the light emitted from the plurality of light-emitting elements is included in the range of 850 nm to 1550 nm. An optical connector characterized by the following features.

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