Optical adapter and optical connector unit

Abstract

To provide an optical adapter for connecting two optical connectors to each other that is capable of suppressing optical loss.SOLUTION: An optical adapter 1 connects two optical connectors to each other in which a plurality of optical fibers are arranged in parallel and held, the optical adapter comprising a first insertion hole 11 into which an inner housing is inserted, each of the two optical connectors being provided with the inner housing. The first insertion hole has a pair of first inner wall surfaces 11a opposing each other. In a cross-sectional view orthogonal to an insertion direction of the two optical connectors, each of the pair of first inner wall surfaces has a first protrusion part 11c on both ends inwardly projected.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present disclosure relates to an optical adapter and an optical connector unit that connect two optical connectors to each other. [Background technology]

[0002] There is known an optical adapter for connecting two optical connectors to each other. For example, Patent Document 1 discloses an optical adapter in which the optical connectors are freely insertable and removable and which connects two optical connectors to each other in a straight line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-204707 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the optical adapter according to Patent Document 1, when the optical connector is inserted at an angle into the optical adapter, the optical connectors do not fit together properly, causing axial misalignment of the optical fiber, which is likely to cause optical loss. If the opening surface of the insertion hole of the optical adapter is narrowed all around to prevent the optical connector from being inserted at an angle into the optical adapter, the contact area between the inner wall of the insertion hole and the outer peripheral surface of the housing of the optical connector increases, generating shavings when the optical connector is inserted or removed, which may cause the optical connectors to not fit together properly, resulting in optical loss.

[0005] An object of the present disclosure is to provide an optical adapter and an optical connector unit capable of suppressing optical loss when two optical connectors are connected to each other. [Means for solving the problem]

[0006] The optical adapter of the present disclosure is an optical adapter that connects two optical connectors in which a plurality of optical fibers are arranged and held in parallel, and has a first insertion hole through which an inner housing provided in each of the two optical connectors is inserted, the first insertion hole having a pair of first inner wall surfaces facing each other, and each of the pair of first inner wall surfaces has a first protrusion protruding inwardly at both ends in a cross-sectional view perpendicular to the insertion direction of the two optical connectors. Effect of the Invention

[0007] According to the present disclosure, it is possible to restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from being improperly mated with each other, resulting in optical loss. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of an optical connector unit according to a first embodiment. [Figure 2A] FIG. 2A is a top view showing the optical adapter according to the first embodiment. [Figure 2B] FIG. 2B is a top view showing a state in which an optical connector is connected to the optical adapter according to the first embodiment. [Figure 3A] FIG. 3A is a cross-sectional view of the optical adapter according to the first embodiment taken along line AA in FIG. 2A. [Figure 3B] FIG. 3B is a cross-sectional view taken along line AA in FIG. 2B in a state in which an optical connector is connected to the optical adapter according to the first embodiment. [Figure 3C] FIG. 3C is a cross-sectional view in the optical connector insertion direction in a state in which the optical connector is connected to the optical adapter according to the first embodiment. [Figure 4A] FIG. 4A is a top view showing an optical adapter according to the second embodiment. [Figure 4B] FIG. 4B is a top view showing a state in which an optical connector is connected to the optical adapter according to the second embodiment. [Figure 5A] FIG. 5A is a cross-sectional view of the optical adapter according to the second embodiment taken along line BB in FIG. 4A. [Figure 5B] FIG. 5B is a cross-sectional view taken along line BB in FIG. 4B in a state in which an optical connector is connected to the optical adapter according to the second embodiment. [Figure 5C] FIG. 5C is a cross-sectional view in the optical connector insertion direction in a state in which the optical connector is connected to the optical adapter according to the second embodiment. [Figure 6A] FIG. 6A is a top view showing an optical adapter according to a third embodiment. [Figure 6B] FIG. 6B is a top view showing a state in which an optical connector is connected to the optical adapter according to the third embodiment. [Figure 7] FIG. 7 is a cross-sectional view of the optical adapter according to the third embodiment in the optical connector insertion direction in a state in which the optical connector is connected to the optical adapter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiment of the present invention] An outline of an embodiment of the present invention will be described. (1) An optical adapter for connecting two optical connectors each having a plurality of optical fibers arranged in parallel, a first insertion hole through which an inner housing of each of the two optical connectors is inserted; The first insertion hole has a pair of first inner wall surfaces opposed to each other, an optical adapter, wherein each of the pair of first inner wall surfaces has a first protrusion protruding inward at both ends in a cross-sectional view perpendicular to the insertion direction of the two optical connectors;

[0010] According to the above configuration, the optical adapter has a first insertion hole through which the inner housings of the two optical connectors are inserted, the first insertion hole has a pair of first inner wall surfaces facing each other, and the pair of first inner wall surfaces has first protrusions protruding inward at both ends. In this way, by narrowing a part of the opening surface of the first insertion hole in the inward direction by the first protrusions, it is possible to restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from being improperly fitted together and causing optical loss.

[0011] (2) The optical adapter according to item (1), wherein each of the pair of first inner wall surfaces has a first groove portion between the two end portions in the cross-sectional view.

[0012] According to the above configuration, the first groove is provided between both ends of the pair of first inner wall surfaces, and the first groove does not come into contact with the outer peripheral surface of the inner housing of the optical connector when the optical connector is inserted or removed. This reduces the contact area between the inner wall of the first insertion hole and the outer peripheral surface of the inner housing of the optical connector, suppressing the generation of shavings caused by contact and wear between the two, and preventing optical loss caused by the optical connectors not being properly fitted together.

[0013] (3) The first insertion hole has a pair of second inner wall surfaces that are perpendicular to the pair of first inner wall surfaces and face each other, The optical adapter according to item (1) or (2), wherein each of the pair of second inner wall surfaces has a second protrusion protruding inwardly at both ends in the cross-sectional view.

[0014] According to the above configuration, the pair of second inner wall surfaces that face each other perpendicularly to the pair of first inner wall surfaces have second protrusions that protrude inward at both ends. In this way, by narrowing a part of the opening surface of the first insertion hole in an inward direction different from that of the first protrusions by the second protrusions in addition to the first protrusions, it is possible to further restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from being properly fitted together and causing optical loss.

[0015] (4) The optical adapter according to item (3), wherein each of the pair of second inner wall surfaces has a second groove portion between the two end portions in the cross-sectional view.

[0016] According to the above configuration, the second groove is provided between both ends of each of the pair of second inner wall surfaces, and the second groove does not come into contact with the outer circumferential surface of the inner housing of the optical connector when the optical connector is inserted or removed. This further reduces the contact area between the inner wall of the first insertion hole and the outer circumferential surface of the inner housing of the optical connector, suppressing the generation of shavings caused by the contact and wear between the two when the optical connector is inserted or removed, and preventing optical loss caused by the optical connectors not being properly fitted together.

[0017] (5) The optical adapter further includes a second insertion hole communicating with the first insertion hole, through which an outer housing of each of the two optical connectors is inserted; the second insertion hole has a pair of third inner wall surfaces opposed to each other, The optical adapter according to any one of items (1) to (4), wherein each of the pair of third inner wall surfaces has a third protrusion protruding inwardly at both ends in the cross-sectional view.

[0018] According to the above configuration, the optical adapter has a second insertion hole through which the outer housings of the two optical connectors are inserted, the second insertion hole has a pair of third inner wall surfaces facing each other, and the pair of third inner wall surfaces has third protrusions protruding inward at both ends. In this way, by narrowing a part of the opening surface of the second insertion hole in the inward direction by the third protrusions, it is possible to restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from being improperly fitted together and causing optical loss.

[0019] (6) The second insertion hole has a pair of fourth inner wall surfaces that are perpendicular to the pair of third inner wall surfaces and face each other, The optical adapter according to item (5), wherein each of the pair of fourth inner wall surfaces has a fourth protrusion protruding inwardly at both ends in the cross-sectional view.

[0020] According to the above configuration, the pair of fourth inner wall surfaces that oppose each other perpendicularly to the pair of third inner wall surfaces have fourth protrusions that protrude inward at both ends. In this way, by narrowing a part of the opening surface of the second insertion portion in an inward direction different from that of the third protrusion by the fourth protrusion in addition to the third protrusion, it is possible to further restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from being properly fitted together and causing optical loss.

[0021] (7) The optical adapter according to any one of (1) to (6), having a total length greater than 20.1 mm in an insertion direction of the two optical connectors.

[0022] According to the above configuration, since the optical adapter has a total length greater than 20.1 mm in the insertion direction of the two optical connectors, even if the optical connector is inserted obliquely into the optical adapter, the tip of the optical connector contacts the inner wall of the optical adapter at the back side in the insertion direction, and the insertion direction is corrected. Therefore, it is possible to restrict the optical connector from being inserted obliquely into the optical adapter, and to prevent the two optical connectors from not being properly fitted together and causing optical loss.

[0023] (8) An optical adapter according to any one of items (1) to (7), the two optical connectors each having the inner housing and the outer housing, The two optical connectors are inserted into the optical adapter and connected to each other, forming an optical connector unit.

[0024] According to the above configuration, it is possible to provide an optical connector unit that prevents optical loss caused by two optical connectors not being properly mated with each other.

[0025] [Details of the embodiment of the present invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, the description of the members having the same reference numbers as those already described in the description of the present embodiment will be omitted. Also, for the sake of convenience, the dimensions of each member shown in the drawings may differ from the actual dimensions of each member.

[0026] (First embodiment) FIG. 1 is a perspective view of an optical connector unit 4 according to the first embodiment.

[0027] The optical connector unit 4 has an optical adapter 1, two optical connectors 2 in which a plurality of optical fibers (not shown) are arranged in parallel and held, and an optical fiber cable 3 in which a plurality of optical fibers are covered with a sheath. As shown in Fig. 1, the two optical connectors 2 to which the optical fiber cable 3 is connected are inserted into the optical adapter 1, whereby they are optically connected to each other.

[0028] Fig. 2A is a top view showing the optical adapter 1 according to the first embodiment. Fig. 2B is a top view showing a state in which an optical connector 2 is connected to the optical adapter 1 according to the first embodiment. Fig. 3A is a cross-sectional view taken along line AA in Fig. 2A of the optical adapter 1 according to the first embodiment. Fig. 3B is a cross-sectional view taken along line AA in Fig. 2B in a state in which the optical connector 2 is connected to the optical adapter 1 according to the first embodiment.

[0029] As shown in FIGS. 2A and 2B, the optical adapter 1 has an overall length L1 of 20.1 mm in the insertion direction of the two optical connectors 2, and is configured so that the inner housing 21 and the outer housing 22 provided on each of the two optical connectors 2 are inserted therethrough.

[0030] As shown in Fig. 3A, the optical adapter 1 has a first insertion hole 11. As shown in Fig. 3B and 3C, the first insertion hole 11 is configured to receive an inner housing 21 provided in each of the two optical connectors 2. For ease of understanding, Fig. 3C shows a state in which only one optical connector 2 is inserted.

[0031] The first insertion hole 11 has a pair of first inner wall surfaces 11a facing each other, and each of the pair of first inner wall surfaces 11a has first protruding portions 11c protruding inwardly from both ends. The pair of first inner wall surfaces 11a are parallel flat surfaces, and have a gap D1 of 5.00 mm to 5.10 mm. The first protrusion 11c protrudes inward (the direction in which the first inner wall surfaces 11a face each other) in a rectangular shape, and has a width W1 of 2.00 mm parallel to the pair of first inner wall surfaces 11a. The first protrusion 11c of one of the pair of first inner wall surfaces 11a and the first protrusion 11c of the other of the pair of first inner wall surfaces 11a are arranged opposite to each other so as to have a gap D2 of 4.94 mm to 4.99 mm. On the other hand, the inner housing 21 of each of the two optical connectors 2 has a width of 4.89 mm to 4.99 mm in the same direction as the gaps D1 and D2. In this way, the first protrusion 11c narrows a part of the opening surface of the first insertion hole 11 in the inward direction, and even if the optical connector 2 is inserted obliquely into the optical adapter 1, it hits the first protrusion 11c. Therefore, the first protrusion 11c restricts the optical connector 2 from being inserted obliquely into the optical adapter 1, and prevents the two optical connectors 2 from being properly fitted together and causing optical loss. The width of the inner housing 21 in the same direction as the gap D2 may be slightly narrower than the gap D2, but the width of the inner housing 21 may be the same as or larger than the gap D2. Even in this case, the inner housing 21 can be inserted into the first insertion hole 11 because both the inner housing 21 and the first insertion hole 11 are slightly deformable.

[0032] Moreover, each of the pair of first inner wall surfaces 11a has a first groove portion 11e between both ends. That is, the first inner wall surface 11a does not have the first protrusion portion 11c in the center, but only at both ends. By having the first groove portion 11e, a gap exists between the first groove portion 11e and the outer peripheral surface of the inner housing 21 of the optical connector 2 when the optical connector is inserted or removed, and they do not come into contact with each other. Therefore, the contact area between the inner wall of the first insertion hole 11 and the outer peripheral surface of the inner housing 21 of the optical connector 2 is reduced, which suppresses the generation of shavings caused by the contact and wear between the two, and prevents the optical connectors 2 from being properly fitted together and causing optical loss.

[0033] Furthermore, the first insertion hole 11 has a pair of second inner wall surfaces 11b that are perpendicular to the pair of first inner wall surfaces 11a and face each other, and each of the pair of second inner wall surfaces 11b has a second protrusion 11d at both ends that protrudes toward the inside (the direction in which the second inner wall surfaces 11b face each other). Here, perpendicular means that two lines extend and cross each other, and does not mean perpendicular in the strict geometric sense. The pair of second inner wall surfaces 11b are curved surfaces of opposing concentric arcs, and have a diameter R1 of 4.80 mm to 4.85 mm. The second protrusion 11d protrudes inward to have a diameter R2 of 4.75 mm to 4.79 mm, which is smaller than the diameter R1, and has a width W2 of 0.65 mm parallel to the pair of second inner wall surfaces 11b. On the other hand, the inner housing 21 provided in each of the two optical connectors 2 has a diameter of 4.75 mm to 4.79 mm. In this way, by further narrowing a part of the opening surface of the first insertion hole 11 in a direction different from the first protrusion 11c by the second protrusion 11d in addition to the first protrusion 11c, the optical connector 2 is configured to abut against the first protrusion 11c or the second protrusion 11d even if it is inserted obliquely into the optical adapter 1. Therefore, the second protrusion 11d further restricts the optical connector 2 from being inserted obliquely into the optical adapter 1, and prevents the two optical connectors 2 from being properly fitted together, causing optical loss. The diameter of the inner housing 21 may be slightly smaller than the diameter R2, but the diameter of the inner housing 21 may be the same as or larger than the diameter R2. Even in this case, the inner housing 21 can be inserted into the first insertion hole 11 because both the inner housing 21 and the first insertion hole 11 are slightly deformable.

[0034] Also, each of the pair of second inner wall surfaces 11b has a second groove portion 11f between both ends. That is, the second inner wall surface 11b has a second protrusion portion 11d only at both ends. Due to the second groove portion 11f, a gap exists between the second groove portion 11f and the outer peripheral surface of the inner housing 21 of the optical connector 2 when the optical connector is inserted or removed, and they are configured not to come into contact with each other. Therefore, the contact area between the inner wall of the first insertion hole 11 and the outer peripheral surface of the inner housing 21 of the optical connector 2 is further reduced, which suppresses the generation of shavings caused by the contact and wear between the two, and prevents the optical connectors 2 from being properly fitted together and causing optical loss.

[0035] Second embodiment FIG. 4A is a top view showing the optical adapter 1 according to the second embodiment. FIG. 4B is a top view showing a state in which the optical connector 2 is connected to the optical adapter 1 according to the second embodiment. FIG. 5A is a BB cross-sectional view of the optical adapter 1 according to the second embodiment in FIG. 4A. FIG. 5B is a BB cross-sectional view of the optical adapter 1 according to the second embodiment in FIG. 4B in a state in which the optical connector 2 is connected to the optical adapter 1 according to the second embodiment. As shown in FIGS. 4A and 4B, the optical adapter 1 has a total length L1 of 20.1 mm in the insertion direction of the two optical connectors 2. Note that the AA cross-sectional view of FIG. 4A has the same structure as the first insertion hole 11 in the first embodiment, so repeated description will not be provided.

[0036] As shown in Fig. 5A, the optical adapter 1 has a second insertion hole 12. The second insertion hole 12 communicates with the first insertion hole 11, and as shown in Figs. 5B and 5C, the outer housings 22 of the two optical connectors 2 are inserted therethrough. For ease of understanding, Fig. 5C shows a state in which only one optical connector 2 is inserted.

[0037] The second insertion hole 12 has a pair of third inner wall surfaces 12a facing each other, and each of the pair of third inner wall surfaces 12a has a third protrusion 12c at both ends that protrudes toward the inside (the direction in which the third inner wall surfaces 12a face each other). The pair of third inner wall surfaces 12a are parallel planes with a gap D3 of 7.80 mm to 7.90 mm. The third protrusion 12c protrudes inward in a rectangular shape and has a width W3 of 2.00 mm parallel to the pair of third inner wall surfaces 12a. The third protrusion 12c of one of the pair of third inner wall surfaces 12a and the third protrusion 12c of the other of the pair of third inner wall surfaces 12a are arranged opposite to each other with a gap D4 of 7.70 mm to 7.75 mm. On the other hand, the outer housing 22 of each of the two optical connectors 2 has a width of 7.50 mm to 7.70 mm in the same direction as the gaps D3 and D4. In this way, the third protrusion 12c narrows a part of the opening surface of the second insertion hole 12 in the inward direction, and even if the optical connector 2 is inserted obliquely into the optical adapter 1, it hits the third protrusion 12c. Therefore, the third protrusion 12c restricts the optical connector 2 from being inserted obliquely into the optical adapter 1, and prevents the two optical connectors 2 from being properly fitted together, causing optical loss. The width of the outer housing 22 in the same direction as the gap D4 may be slightly narrower than the gap D4, or the width of the gap D4 and the outer housing 22 may be the same. Even in this case, the outer housing 22 can be inserted into the second insertion hole 12 because both the outer housing 22 and the second insertion hole 12 are slightly deformable.

[0038] Furthermore, the second insertion hole 12 has a pair of fourth inner wall surfaces 12b that are perpendicular to the pair of third inner wall surfaces 12a and face each other, and each of the pair of fourth inner wall surfaces 12b has a fourth protrusion 12d at both ends that protrudes toward the inside (the direction in which the fourth inner wall surfaces 12b face each other). Here, perpendicular means that two lines extend and cross each other, and does not mean perpendicular in the strict geometric sense. The pair of fourth inner wall surfaces 12b are curved surfaces of opposing concentric arcs, and have a diameter R3 of 6.60 mm to 6.70 mm. The fourth protrusion 12d protrudes inward to have a diameter R4 of 6.51 mm to 6.55 mm, which is smaller than the diameter R3, and has a width W4 of 1.00 mm parallel to the pair of fourth inner wall surfaces 12b. On the other hand, the outer housing 22 provided in each of the two optical connectors 2 has a diameter of 6.10 mm to 6.30 mm, which is slightly narrower than the diameter R4. In this way, by further narrowing a part of the opening surface of the second insertion hole 12 in a direction different from the third protrusion 12c by the fourth protrusion 12d in addition to the third protrusion 12c, the optical connector 2 is configured to abut against the third protrusion 12c or the fourth protrusion 12d even if it is inserted obliquely into the optical adapter 1. Therefore, the fourth protrusion 12d further restricts the optical connector 2 from being inserted obliquely into the optical adapter 1, and prevents the two optical connectors 2 from being improperly mated with each other, causing optical loss.

[0039] Third embodiment Fig. 6A is a top view showing the optical adapter 1 according to the third embodiment. Figs. 6B and 7 are a top view showing a state in which the optical connector 2 is connected to the optical adapter 1 according to the third embodiment, and a cross-sectional view in the optical connector insertion direction. Note that the AA cross-sectional view and the BB cross-sectional view in Fig. 6A have the same structure as the first insertion hole 11 in the first embodiment and the second insertion hole 12 in the second embodiment, so they will not be described repeatedly. Also, Fig. 7 shows a state in which only one optical connector 2 is inserted for ease of understanding.

[0040] 6A and 6B, the optical adapter 1 has a total length L2 of 25.1 mm in the insertion direction of the two optical connectors 2, which is larger than the total length L1 of the first and second embodiments. Therefore, even if the optical connector 2 is inserted obliquely into the optical adapter 1, the tip of the optical connector 2 contacts the inner wall of the optical adapter 1 at the back side in the insertion direction, and the insertion direction is corrected. Therefore, it is possible to restrict the optical connector 2 from being inserted obliquely into the optical adapter 1, and to prevent the two optical connectors 2 from not being properly fitted together and causing optical loss.

[0041] Although the embodiment of the present invention has been described above, it goes without saying that the technical scope of the present invention should not be interpreted as being limited by the description of the present embodiment. This embodiment is merely an example, and it is understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. Thus, the technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. For example, the first protrusion 11c and the second protrusion 11d of the first embodiment and the third protrusion 12c and the fourth protrusion 12d of the second embodiment protrude in a rectangular shape, but even if the optical connector 2 is inserted obliquely into the optical adapter 1, it is sufficient that the first protrusion 11c, the second protrusion 11d, the third protrusion 12c, and the fourth protrusion 12d are abutted against each other, and the shapes of the first protrusion 11c, the second protrusion 11d, the third protrusion 12c, and the fourth protrusion 12d may be other protrusion shapes such as a sawtooth shape, a triangular shape, an elliptical shape, and the like. [Explanation of symbols]

[0042] 1: Optical adapter 2: Optical connector 3: Fiber optic cable 4: Optical connector unit 11: First insertion hole 11a: First inner wall surface 11b: Second inner wall surface 11c: 1st protrusion 11d: Second protrusion 11e: First groove 11f: Second groove 12: Second insertion hole 12a: Third inner wall surface 12b: 4th inner wall 12c: Third protrusion 12d: 4th protrusion 21: Inner housing 22: Outer housing L1, L2: Total length D1, D2, D3, D4: gap W1, W2, W3, W4: Width R1, R2, R3, R4: diameter

Claims

1. An optical adapter for connecting two optical connectors, each of which holds a plurality of optical fibers arranged in parallel, comprising: a first insertion hole through which an inner housing of each of the two optical connectors is inserted; The first insertion hole has a pair of first inner wall surfaces opposed to each other, Each of the pair of first inner wall surfaces has a first protrusion protruding inward at first both end portions that are both end portions of each of the pair of first inner wall surfaces in a cross-sectional view perpendicular to the insertion direction of the two optical connectors, Each of the pair of first inner wall surfaces has a first groove portion between the first end portions in the cross-sectional view, The first insertion hole has a pair of second inner wall surfaces that are perpendicular to the pair of first inner wall surfaces and face each other, Each of the pair of second inner wall surfaces has a second protruding portion protruding toward an inner direction at second both ends, which are both ends of each of the pair of second inner wall surfaces in the cross-sectional view, Each of the pair of second inner wall surfaces has a second groove portion between the second end portions in the cross-sectional view.

2. The optical adapter further includes a second insertion hole communicating with the first insertion hole, through which an outer housing of each of the two optical connectors is inserted; The second insertion hole has a pair of third inner wall surfaces opposed to each other, The optical adapter of claim 1, wherein each of the pair of third inner wall surfaces has a third protrusion protruding inward at both third ends, which are both ends of each of the pair of third inner wall surfaces, when viewed in cross-section.

3. the second insertion hole has a pair of fourth inner wall surfaces that are perpendicular to the pair of third inner wall surfaces and face each other, 3. The optical adapter according to claim 2, wherein each of the pair of fourth inner wall surfaces has a fourth protrusion protruding inward at both fourth ends, which are both ends of each of the pair of fourth inner wall surfaces, when viewed in cross-section.

4. 4. The optical adapter according to claim 1, wherein the optical adapter has a total length greater than 20.1 mm in an insertion direction of the two optical connectors.

5. An optical adapter according to claim 2 or claim 3, the two optical connectors each having the inner housing and the outer housing, The two optical connectors are inserted into the optical adapter and connected to each other, forming an optical connector unit.

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