Optical transceiver

Abstract

To suppress a leakage of an unnecessary electromagnetic wave.SOLUTION: An optical transmission receiver includes an attenuation structure 42 that is provided so as to attenuate an electromagnetic wave into an intermediate space 38 into which an optical fiber 20 passes through. An internal space 32 is communicated to a first direction D1 between a photoelectric element 16 and an optical connector 10 and is surrounded by a conductive surface even in any directions which are orthogonal to the first direction D1. The attenuation structure 42 is a column structure formed by a plurality of conductive columns 44 conducted to the conductive surface. In the column structure, the plurality of conductive columns 44 is extended to a second direction D2 that is orthogonal to the first direction D1, and the plurality of conductive columns 44 is arranged to a plurality of points P in plan view along the second direction D2. The plurality of points P is at a top of a plurality of squares Q of which one side of the adjacent squares Q are shared. The plurality of squares Q is arranged to at least the first direction D1, and the optical fiber 20 passes through at least a pair of them that is adjacent to the first direction D1 of the plurality of squares Q.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to an optical transceiver.

Background Art

[0002] In optical fiber transmission, optical transceivers (optical transceiver modules) are widely used (Patent Documents 1 to 4). An optical transceiver inputs and outputs optical signals through an optical connector, inputs and outputs electrical signals through an electrical connector, and converts optical signals and electrical signals with an optoelectronic device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Inside an optical transceiver, unnecessary electromagnetic waves are generated, and it is necessary to suppress their leakage. In particular, since optical connectors are often made of resin and are likely to leak unnecessary electromagnetic waves, it is required to attenuate the electromagnetic waves propagating to the optical connector. However, since a space for an optical fiber connecting the optoelectronic device and the optical connector is required, it is difficult to arrange electromagnetic wave shields such as metal or radio wave absorbing materials.

[0005] An object of the present invention is to suppress the leakage of unnecessary electromagnetic waves.​​​​​​The optical transceiver comprises an optical connector, a photoelectric element, an optical fiber connecting the optical connector and the photoelectric element, a metal housing having an internal space in which the optical connector, the photoelectric element, and the optical fiber are housed and electromagnetic waves propagate within the internal space, and an attenuation structure provided in the intermediate space through which the optical fiber passes within the internal space to attenuate the electromagnetic waves, wherein the internal space is continuous in a first direction between the photoelectric element and the optical connector and is surrounded by conductive surfaces in any direction perpendicular to the first direction, and the attenuation structure is either a column structure consisting of a plurality of conductive pillars conductive to the conductive surface or a plate structure consisting of a plurality of conductive plates conductive to the conductive surface, wherein in the column structure, the plurality of conductive pillars are connected in a second direction perpendicular to the first direction The plurality of conductive columns extend, and in a plan view along the second direction, they are arranged at a plurality of points, the plurality of points are at the vertices of a plurality of quadrilaterals sharing one side of adjacent quadrilaterals, the plurality of quadrilaterals are aligned at least in the first direction, and the optical fiber passes through at least one pair of the plurality of quadrilaterals that are adjacent in the first direction, and in the plate structure, the plurality of conductive plates are arranged with their front and back surfaces facing each other in a third direction perpendicular to the first and second directions, the plurality of conductive plates are spaced apart from each other in the third direction, the intermediate space is divided into a plurality of spaces aligned in the third direction, at least one of the plurality of spaces is small in width in the third direction to the extent that it hinders the propagation of the electromagnetic waves, and the optical fiber passes through at least one of the plurality of spaces. [Brief explanation of the drawing]

[0007] [Figure 1] This is an exploded perspective view of an optical transceiver according to the first embodiment. [Figure 2] This is a partial cross-sectional view of an optical transceiver according to the first embodiment. [Figure 3] This is a perspective view of the conductive surface of a waveguide that simulates a metal casing. [Figure 4] This is a perspective view of the attenuation structure and optical fiber. [Figure 5] This is a side view of the damping structure. [Figure 6]This is a plan view of the damping structure. [Figure 7] This figure shows the frequency dependence of a waveguide simulating a metal enclosure. [Figure 8] This is a perspective view of the protrusion and damping structure of a modified example of the first embodiment. [Figure 9] This is a perspective view of a plurality of conductive columns and optical fibers of an optical transceiver according to the second embodiment. [Figure 10] This is a plan view of multiple conductive columns and optical fibers. [Figure 11] This figure shows the frequency dependence of a waveguide simulating a metal enclosure. [Figure 12] This is a perspective view of the attenuation structure of an optical transceiver according to the third embodiment. [Figure 13] This is a side view of the damping structure. [Figure 14] This is a plan view of the damping structure. [Figure 15] This figure shows the frequency dependence of a waveguide simulating a metal enclosure. [Figure 16] This is an exploded perspective view of the protrusion and damping structure of a modified example of the third embodiment. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the drawings. Components denoted by the same reference numerals in all figures have the same or equivalent function, and repeated explanations will be omitted. Note that the size of the figures does not necessarily correspond to the magnification.

[0009] [First Embodiment] FIG. 1 is an exploded perspective view of an optical transceiver according to the first embodiment. Optical transceivers (optical transceiver modules) for optical fiber transmission have been becoming faster, smaller, and less costly with the spread of recent broadband networks. The bit rate has also increased to 100 Gbit / s or higher up to 400 Gbit / s, and for 400 Gbit / s optical transceivers, reduction in case volume and the number of components has been progressing, such as in the QSFP-DD or OSFP which are MSA (Multi Source Agreement) standards.

[0010] For network devices equipped with optical transceivers, it is required to suppress the intensity of unnecessary electromagnetic waves generated by the device to below the limit value specified by regulations. In the United States, it is necessary to satisfy the limit value of 53.9 dB(μV / m) specified in the FCC Part 15 Subpart B standard (Class B standard, at a distance of 3 m, for the frequency range of 1 GHz to 40 GHz).

[0011] [Optical connector] FIG. 2 is a partial cross-sectional view of the optical transceiver according to the first embodiment. The optical transceiver has an optical connector 10. The optical connector 10 is an MPO (Multi-Fiber Push On) connector. Since the main materials of the optical connector 10 and the MT (Mechanically Transferable) ferrule 12 inside it are resin, electromagnetic wave radiation to the outside is likely to occur. The optical connector 10 has a guide pin 14.

[0012] [Optoelectronic device] The optical transceiver has one or more optoelectronic devices 16. The optoelectronic device 16 is an optical transmission subassembly (TOSA) 16A and an optical reception subassembly (ROSA) 16B. The optoelectronic device 16 is part of a transmission and reception circuit that is configured to generate electromagnetic waves. The frequency of the electromagnetic waves is a frequency corresponding to the modulation rate of the digital modulation signal transmitted by the transmission and reception circuit. In a 400 Gbit / s optical transceiver, since an electrical serial data signal with a modulation rate of 26.56 Gbaud (exactly 26.5625 Gbaud) is used, unwanted electromagnetic waves with a frequency of 26.56 GHz (exactly 26.5625 GHz) corresponding to that modulation rate are generated. The position of the optoelectronic device 16 varies according to the circuit design. The optoelectronic device 16 is fixed by a fixing bracket 18.

[0013] [Optical fiber] The optical transceiver has one or more optical fibers 20. The optical fiber 20 connects the optical connector 10 and the optoelectronic device 16. It is preferable that the arrangement of the optical fiber 20 can be freely changed according to the position of the optoelectronic device 16.

[0014] [Printed circuit board] The optical transceiver has a printed circuit board 22. The printed circuit board 22 has an electrical connector 24 (for example, a card edge connector) at its end. The printed circuit board 22 has a wiring pattern (not shown) to which the optoelectronic device 16 is electrically connected. A flexible printed circuit board (FPC board) 26 is used for the electrical connection. An IC 28 (for example, a digital signal processor) is mounted on the printed circuit board 22. Due to the noise (for example, switching noise) of the IC 28, unwanted electromagnetic waves are generated at frequencies above GHz. Therefore, design techniques for reducing the radiation of unwanted electromagnetic waves outside the device are important for both the network device and the optical transceiver.

[0015] In an optical transceiver, the main source of unwanted electromagnetic wave excitation is IC28, which amplifies and outputs the electrical serial data signal (modulated signal). Unlike clock signals, ideally random serial data signals do not contain repeating signal patterns, and therefore do not have large peak intensity on the frequency spectrum (spread spectrum). However, in the amplification circuit inside IC28, switching noise is generated due to the nonlinearity of the transistors, and when the frequency spectrum of the output signal is observed, a large peak occurs at the frequency corresponding to the modulation rate (or modulation speed, symbol rate). This noise is radiated into space from the printed circuit board 22 and emitted outside the device as unwanted electromagnetic wave.

[0016] [Metal casing] The optical transceiver has a metal housing 30. The metal housing 30 includes a fitted upper case 30A and a lower case 30B. There is an opening at the front of the metal housing 30 for housing an optical connector 10, which is fixed therein. The end of a printed circuit board 22 (electrical connector 24) protrudes from an opening at the rear of the metal housing 30 (e.g., the lower case 30B). The metal housing 30 constitutes a waveguide (e.g., a rectangular waveguide). The inner surface of the metal housing 30 (waveguide) is a conductive surface.

[0017] Figure 3 is a perspective view of the conductive surface of a waveguide simulating a metal housing 30. The metal housing 30 has an internal space 32 that houses the optical connector 10, the photoelectric element 16, and the optical fiber 20. The internal space 32 is continuous in a first direction D1 between the photoelectric element 16 and the optical connector 10. The internal space 32 is surrounded by conductive surfaces in any direction perpendicular to the first direction D1. Electromagnetic waves propagate within the internal space 32. The conductive surface has a width a of 15.3 mm and a height b of 7.0 mm, corresponding to a QSFP-DD. The waveguide is assumed to be sufficiently long.

[0018] The internal space 32 includes a first space 34 in which the optical connector 10 is housed. The internal space 32 also includes a second space 36 in which the photoelectric element 16 is housed. The printed circuit board 22 is placed in the second space 36. The ends of the printed circuit board 22 (electrical connector 24) are exposed from the metal housing 30.

[0019] The internal space 32 includes an intermediate space 38 through which the optical fiber 20 passes. The intermediate space 38 is located between the first space 34 and the second space 36. As shown in Figure 2, the conductive surface includes a protrusion 40 that projects into the intermediate space 38 in the second direction D2 (height direction) perpendicular to the first direction D1. As a result, as shown in Figure 3, the height H of the intermediate space 38 (5 mm or less, more preferably 3.745 mm or less) is smaller than the height b of the first space 34 and the second space 36 in the second direction D2. The height H of the intermediate space 38 is less than half the wavelength of the electromagnetic wave propagating in the internal space 32 in the second direction D2. In contrast, the height b of the first space 34 and the second space 36 (e.g., 7 mm) is greater than half the wavelength of the electromagnetic wave (5.65 mm) in the second direction D2. The length L of the intermediate space 38 is, for example, 10 mm.

[0020] Assuming the frequency of unwanted electromagnetic waves is 26.56 GHz, the modes propagating inside the waveguide are TE10 (mode 1), TE20 (mode 2), TE01 (mode 3), TE11 (mode 4), and TM11 (mode 5). To block the TE01 mode, the height H of the intermediate space 38 must be at least half the wavelength at a frequency of 26.56 GHz.

[0021] According to the theoretical formula, if the height H of the intermediate space 38 is 5 mm, the cutoff frequency of the TE01 mode (mode 3) becomes 30 GHz, and an inhibitory effect is obtained. However, when the height H is 5 mm, the attenuation obtained for each 1 mm increase in the length L of the intermediate space 38 is calculated to be 2.53 dB, requiring a relatively long intermediate space 38. When the height H of the intermediate space 38 is 3.745 mm, the cutoff frequency of the TE01 mode rises to 40 GHz. When the height H is 3.745 mm, the attenuation obtained for each 1 mm increase in the length L of the intermediate space 38 increases to 5.44 dB, making inhibition possible with a relatively short intermediate space 38.

[0022] To further suppress the leakage of unwanted electromagnetic waves from the optical connector 10, it is desirable to place shielding materials such as metal or radio wave absorbing materials in the intermediate space 38 to minimize the gaps in the vertical, horizontal, and vertical directions, and to pass the optical fiber 20 through or sandwich the optical fiber 20 between them. However, this reduces the degree of freedom in arranging the optical fiber 20, making it difficult to connect to the photoelectric element 16 and complicating assembly work. Therefore, in this embodiment, the optical transceiver has an attenuation structure 42. This makes it possible to obtain the effect of suppressing the other four modes.

[0023] [Damping structure] Figure 4 is a perspective view of the attenuation structure 42 and the optical fiber 20. Figure 5 is a side view of the attenuation structure 42. The attenuation structure 42 is located in the intermediate space 38 of the internal space 32. The attenuation structure 42 is designed to attenuate electromagnetic waves. The attenuation structure 42 is a column structure consisting of a plurality of conductive columns 44 (e.g., metal columns) that conduct to the conductive surface. The plurality of conductive columns 44 extend in the second direction D2.

[0024] Figure 6 is a plan view of the damping structure 42. Multiple conductive columns 44 are arranged at multiple points P in a plan view along the second direction D2. The multiple points P are arranged in a square grid. The multiple points P are at the vertices of multiple quadrilaterals Q that share one side of adjacent quadrilaterals Q. Each of the multiple quadrilaterals Q is a rectangle (e.g., a square). The multiple quadrilaterals Q are arranged at least in the first direction D1 and also in the third direction D3 (width direction) which is perpendicular to the first direction D1 and the second direction D2. Multiple (at least three) conductive columns 44 are arranged in the first direction D1. Multiple (e.g., four) conductive columns 44 are arranged in the third direction D3. The gap between the damping structure 42 and the conductive surface in the third direction D3 is smaller than the length of one side of each of the multiple quadrilaterals Q.

[0025] The optical fiber 20 passes through the attenuation structure 42. The optical fiber 20 passes through at least one pair of quadrilaterals Q adjacent to each other in the first direction D1. If a conductive wire such as a copper wire is used instead of the dielectric optical fiber 20, a propagation mode (TEM mode) different from the five modes described above will occur, and a sufficiently large inhibitory effect against unwanted electromagnetic waves as described above will not be obtained.

[0026] [Frequency Dependence] Figure 7 shows the frequency dependence of a waveguide simulating a metal housing 30. The frequency dependence was calculated using a three-dimensional electromagnetic field analysis tool. The height H of the intermediate space 38 was set to 3.745 mm, and the length L of the intermediate space 38 was set to 10 mm. The conductive pillars 44 were cylindrical with an outer diameter of 0.75 mm, and the distance between the centers of the conductive pillars 44 was set to 3.36 mm. The spacing between the conductive pillars 44 was 2.61 mm (less than or equal to 3.0 mm). The gap G between the conductive pillars 44 and the conductive surface was 2.235 mm (less than or equal to 3.0 mm). The small signal transmission characteristic (S21) at a frequency of 26.56 GHz was -40 dB or less, indicating that a sufficiently large inhibitory effect against unwanted electromagnetic waves is obtained.

[0027] Furthermore, analysis using a three-dimensional electromagnetic field analysis tool that simulates an electromagnetic reverberation chamber (RVC) revealed that the optical transceiver according to this embodiment can reduce unwanted electromagnetic waves at a frequency of 26.56 GHz by approximately 40 dB, demonstrating a sufficiently large inhibitory effect. This result is consistent with the small signal transmission characteristics (S21) shown in Figure 7.

[0028] According to this embodiment, in an optical transceiver that generates unwanted electromagnetic waves, the intermediate space 38 can block unwanted electromagnetic waves while ensuring a size sufficient for arranging the optical fiber 20, thereby providing an optical transceiver that achieves both reduction of unwanted electromagnetic waves and freedom in arranging the optical fiber 20.

[0029] [Modified version of the first embodiment] Figure 8 is a perspective view of the protrusion and damping structure of a modified example of the first embodiment. In this modified example, a conductor 146 is attached to the inner surface of a metal housing without a protrusion to form the protrusion 140. The conductor 146 may be made entirely of metal, or it may be a plated film covering a resin plate, or it may be conductive rubber or conductive nonwoven fabric. A conductive adhesive can be used to attach the conductor 146. Multiple conductive columns 144 are interposed between a pair of conductors 146. One conductor 146 and the multiple conductive columns 144 may be integrally formed of metal, while the other conductor 146 may be formed of conductive rubber or conductive nonwoven fabric.

[0030] Since the conductor 146 is a separate component from the metal housing, the material and manufacturing process can be selected without being limited by the material and manufacturing process of the metal housing, making it possible to provide an inexpensive, high-quality optical transceiver with an unwanted electromagnetic wave blocking structure.

[0031] [Second Embodiment] Figure 9 is a perspective view of a plurality of conductive columns and optical fibers of an optical transceiver according to the second embodiment. The conductive surface of the waveguide, which simulates a metal housing, is shown by a dashed line. This embodiment differs from the first embodiment in the arrangement of the plurality of conductive columns 244.

[0032] Figure 10 is a plan view of multiple conductive pillars 244 and optical fibers 220. Multiple points P, where multiple conductive pillars 244 are lined up, are at the vertices of multiple quadrilaterals Q that share one side of adjacent quadrilaterals Q. Each of the multiple quadrilaterals Q is a parallelogram other than a rectangle, with a pair of opposite sides parallel to the first direction D1. In other words, the multiple points P are arranged in a regular triangular grid. Multiple optical fibers 220 pass through at least one pair (e.g., two pairs) of the multiple quadrilaterals Q that are adjacent to the first direction D1.

[0033] At least three conductive columns 244 are arranged in the first direction D1. For example, four conductive columns 244 are arranged in a zigzag pattern in the third direction D3. The conductive columns 244 have a center-to-center distance of 3.73 mm, a spacing of 2.98 mm (3.0 mm or less), and a gap G between the conductive column 244 and the conductive surface of approximately 2.43 mm (3.0 mm or less). The outer diameter of the conductive column 244 and the height and length of the intermediate space 238 are the same as in the first embodiment.

[0034] Figure 11 shows the frequency dependence of a waveguide simulating a metal enclosure. The frequency dependence was calculated using a three-dimensional electromagnetic field analysis tool. The small signal pass-through characteristic (S21) at a frequency of 26.56 GHz is less than -37 dB, indicating that a sufficiently large inhibitory effect against unwanted electromagnetic waves is obtained.

[0035] [Third Embodiment] Figure 12 is a perspective view of the attenuation structure of an optical transceiver according to the third embodiment. The conductive surface of the waveguide, which simulates a metal housing, is shown by a dashed line. Figure 13 is a side view of the attenuation structure. Figure 14 is a plan view of the attenuation structure.

[0036] The attenuation structure 342 is a plate structure consisting of a plurality of conductive plates 348 that are conductive to the conductive surface. The plurality of conductive plates 348 are arranged with their front and back surfaces facing in a third direction D3 that is perpendicular to the first direction D1 and the second direction D2. The plurality of conductive plates 348 are spaced apart from each other in the third direction D3. The plurality of conductive plates 348 divide the intermediate space 338 into a plurality of spaces S aligned in the third direction D3. At least one of the plurality of spaces S is small enough in the width of the third direction D3 to hinder the propagation of electromagnetic waves. An optical fiber passes through at least one of the plurality of spaces S. The gap G between the attenuation structure 342 and the conductive surface in the third direction D3 is smaller than the spacing between the plurality of conductive plates 348.

[0037] The conductive plate 348 had a thickness of 0.75 mm and a length of 7.22 mm. The distance between the centers of the conductive plates 348 was 3.73 mm, and the spacing was 2.98 mm (3.0 mm or less). The gap G between the conductive plate 348 and the conductive surface was approximately 2.43 mm (3.0 mm or less). The height and length of the intermediate space 338 were the same as in the first embodiment.

[0038] Figure 15 shows the frequency dependence of a waveguide simulating a metal enclosure. The frequency dependence was calculated using a three-dimensional electromagnetic field analysis tool. The small signal pass-through characteristic (S21) at a frequency of 26.56 GHz is less than -58 dB, indicating that a sufficiently large inhibitory effect against unwanted electromagnetic waves is obtained.

[0039] Furthermore, analysis using a three-dimensional electromagnetic field analysis tool that simulates an electromagnetic reverberation chamber (RVC) revealed that the optical transceiver according to this embodiment can reduce unwanted electromagnetic waves at a frequency of 26.56 GHz by approximately 60 dB, demonstrating a sufficiently large inhibitory effect. This result is consistent with the small signal transmission characteristics (S21) shown in Figure 15.

[0040] [Modified example of the third embodiment] Figure 16 is an exploded perspective view of the protrusion and damping structure of a modified example of the third embodiment. In this modified example, a conductor 446 is attached to the inner surface of a metal housing without a protrusion to form the protrusion 440. The conductor 446 may be made entirely of metal, or it may be a plated film covering a resin plate, or it may be conductive rubber or conductive nonwoven fabric. A conductive adhesive can be used to attach the conductor 446. Alternatively, the conductor 446 and the multiple conductive plates 448 may be formed by folding conductive nonwoven fabric.

[0041] [Summary of the Embodiment] (1) The optical transceiver comprises an optical connector 10, a photoelectric element 16, an optical fiber 20 connecting the optical connector 10 and the photoelectric element 16, a metal housing 30 having an internal space 32 that houses the optical connector 10, the photoelectric element 16 and the optical fiber 20, and through which electromagnetic waves propagate, and an attenuation structure 42 provided in an intermediate space 38 of the internal space 32 through which the optical fiber 20 passes to attenuate the electromagnetic waves, wherein the internal space 32 is continuous in a first direction D1 between the photoelectric element 16 and the optical connector 10 and is surrounded by conductive surfaces in any direction perpendicular to the first direction D1, and the attenuation structure 42 is either a column structure consisting of a plurality of conductive pillars 44 that are conductive to the conductive surface or a plate structure consisting of a plurality of conductive plates 348 that are conductive to the conductive surface, and in the column structure, the plurality of conductive pillars 44 are perpendicular to the first direction D1 The plurality of conductive columns 44 extend in a second direction D2, and in a plan view along the second direction D2, they are arranged at a plurality of points P, the plurality of points P are at the vertices of a plurality of quadrilaterals Q that share one side of adjacent quadrilaterals Q, the plurality of quadrilaterals Q are aligned in at least the first direction D1, and the optical fiber 20 passes through at least one pair of the plurality of quadrilaterals Q adjacent to the first direction D1, and in the plate structure, the plurality of conductive plates 348 are arranged with their front and back surfaces facing in a third direction D3 perpendicular to the first direction D1 and the second direction D2, the plurality of conductive plates 348 are spaced apart from each other in the third direction D3, the intermediate space 38 is divided into a plurality of spaces S aligned in the third direction D3, at least one of the plurality of spaces S is small enough in the width of the third direction D3 to hinder the propagation of electromagnetic waves, and the optical fiber 20 passes through at least one of the plurality of spaces S. The attenuation structure 42 can attenuate electromagnetic waves, thereby suppressing the leakage of unwanted electromagnetic waves. (2) An optical transceiver as described in (1), wherein the photoelectric element 16 is part of a transmitting / receiving circuit that generates electromagnetic waves, and the frequency of the electromagnetic waves is a frequency corresponding to the modulation rate of a digital modulation signal transmitted by the transmitting / receiving circuit. (3) An optical transceiver as described in (1) or (2), wherein the internal space 32 includes a first space 34 in which the optical connector 10 is housed and a second space 36 in which the photoelectric element 16 is housed, and the intermediate space 38 is located between the first space 34 and the second space 36 and is smaller than the first space 34 and the second space 36 in height in the second direction D2. (4) An optical transceiver as described in (3), wherein the first space 34 and the second space 36 are greater than half the wavelength of the electromagnetic wave at the height in the second direction D2. (5) An optical transceiver as described in any one of (1) to (4), wherein the intermediate space 38 is less than half the wavelength of the electromagnetic wave at the height of the second direction D2. (6) An optical transceiver as described in any one of (1) to (5), wherein the attenuation structure 42 is the column structure, and the plurality of quadrilaterals Q are arranged in the first direction D1 and the third direction D3. An optical transceiver as described in (7)(6), wherein the plurality of points P are arranged in a square grid and each of the plurality of quadrilaterals Q is a rectangle. An optical transceiver as described in (8)(6), wherein the plurality of points P are arranged in a regular triangular grid, each of the plurality of quadrilaterals Q is a parallelogram other than a rectangle, and a pair of opposite sides of the parallelogram are parallel to the first direction D1. (9) An optical transceiver as described in any one of (1) to (8), wherein the gap G between the attenuation structure 42 and the conductive surface in the third direction D3 is smaller than the length of one side of each of the plurality of quadrilaterals Q and smaller than the spacing between the plurality of conductive plates 348. An optical transceiver as described in any one of (1) to (9), wherein the conductive surface includes a convex portion 40 that protrudes into the intermediate space 38 in the second direction D2. An optical transceiver as described in (11)(10), wherein the protrusion 140 is composed of a conductor 146 attached to the conductive surface. (12) An optical transceiver as described in any one of (1) to (12), further comprising a printed circuit board 22 disposed in the second space 36 and having an end exposed from the metal housing 30, wherein the printed circuit board 22 has an electrical connector 24 at its end. [Explanation of symbols]

[0042] 10 Optical connector, 12 MT ferrule, 14 Guide pin, 16 Photoelectric element, 16A Optical transmitting subassembly, 16B Optical receiving subassembly, 18 Fixing bracket, 20 Optical fiber, 22 Printed circuit board, 24 Electrical connector, 26 Flexible board, 28 IC, 30 Metal housing, 30A Upper case, 30B Lower case, 32 Internal space, 34 First space, 36 Second space, 38 Intermediate space, 40 Protrusion, 42 Attenuation structure, 44 Conductive column, 140 Protrusion, 144 Conductive column, 146 Conductor, 220 Optical fiber, 238 Intermediate space, 244 Conductive column, 338 Intermediate space, 342 Attenuation structure, 348 Conductive plate, 440 Protrusion, 446 Conductor, 448 Conductive plate, a Width, b Height, D1 First direction, D2 Second direction, D3 Third direction, G gap, H height, L length, P point, Q quadrilateral, S space.

Claims

1. Optical connector and Photoelectric element, The optical fiber connecting the optical connector and the photoelectric element, A metal housing having an internal space in which the optical connector, the photoelectric element, and the optical fiber are housed, and in which electromagnetic waves propagate. An attenuation structure is provided in the intermediate space through which the optical fiber passes within the aforementioned internal space to attenuate the electromagnetic wave, It has, The internal space is continuous in a first direction between the photoelectric element and the optical connector, and is surrounded by conductive surfaces in any direction perpendicular to the first direction. The damping structure is either a column structure consisting of a plurality of conductive pillars that are conductive to the conductive surface, or a plate structure consisting of a plurality of conductive plates that are conductive to the conductive surface. In the aforementioned column structure, The plurality of conductive columns extend in a second direction perpendicular to the first direction, The plurality of conductive columns are arranged at multiple points in a plan view along the second direction, The aforementioned points are located at the vertices of multiple quadrilaterals that share one side with adjacent quadrilaterals. The plurality of quadrilaterals are arranged in at least the first direction, The optical fiber passes through at least one pair of the plurality of quadrilaterals that are adjacent in the first direction. In the aforementioned plate structure, The plurality of conductive plates are arranged with their front and back surfaces facing in a third direction perpendicular to the first and second directions. The plurality of conductive plates are separated from each other in the third direction and face each other, dividing the intermediate space into a plurality of spaces arranged in the third direction. At least one of the aforementioned plurality of spaces is small in width in the third direction to the extent that it hinders the propagation of the electromagnetic wave. An optical transceiver through which the optical fiber passes over at least one of the aforementioned plurality of spaces.

2. An optical transceiver according to claim 1, The aforementioned photoelectric element is part of a transmitting and receiving circuit that generates electromagnetic waves, An optical transceiver in which the frequency of the electromagnetic wave corresponds to the modulation rate of the digital modulation signal transmitted by the transmitting and receiving circuit.

3. An optical transceiver according to claim 1, The internal space includes a first space in which the optical connector is housed and a second space in which the photoelectric element is housed. The aforementioned intermediate space is located between the first space and the second space and is smaller in height in the second direction than the first space and the second space, and is an optical transceiver.

4. An optical transceiver according to claim 3, The first space and the second space are optical transceivers in which the height in the second direction is greater than half the wavelength of the electromagnetic wave.

5. An optical transceiver according to claim 1, The aforementioned intermediate space is an optical transceiver in which the height in the second direction is less than half the wavelength of the electromagnetic wave.

6. An optical transceiver according to claim 1, The damping structure is the column structure, The aforementioned plurality of rectangles are optical transceivers arranged in the first and third directions.

7. An optical transceiver according to claim 6, The aforementioned multiple points are arranged in a square grid, Each of the aforementioned quadrilaterals is a rectangular optical transceiver.

8. An optical transceiver according to claim 6, The aforementioned multiple points are arranged in a regular triangular grid, Each of the aforementioned quadrilaterals is a parallelogram excluding rectangles, An optical transceiver in which a pair of opposing sides of the parallelogram are parallel to the first direction.

9. An optical transceiver according to any one of claims 1 to 8, An optical transceiver in which the gap between the attenuation structure and the conductive surface in the third direction is smaller than the length of one side of each of the plurality of rectangles and smaller than the spacing between the plurality of conductive plates.

10. An optical transceiver according to any one of claims 1 to 8, The conductive surface includes a convex portion that protrudes into the intermediate space in the second direction, making it an optical transceiver.

11. An optical transceiver according to claim 10, The aforementioned protrusion is an optical transceiver composed of a conductor attached to the conductive surface.

12. An optical transceiver according to claim 3 or 4, The second space further comprises a printed circuit board whose end is exposed from the metal housing, The printed circuit board is an optical transceiver equipped with an electrical connector at its end.

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