Optical coupling section and optical switch

Abstract

An optical coupling unit according to the present disclosure comprises: a first ferrule in which core centers of single core fibers are disposed on the same circumference of the ferrule and which has an end surface formed into a convex spherical surface in a ferrule central axis direction together with end surfaces of the single core fibers; and a second ferrule in which a core center of a single core fiber is disposed on a circumference having the same diameter as the abovementioned circumference and which has an end surface formed into a convex spherical surface in a ferrule central axis direction together with an end surface of the single core fiber. The respective central axes of the ferrules align with each other. The optical coupling unit has a cylindrical sleeve in which the first and second ferrules are inserted such that the end surfaces formed into the convex spherical surface face each other, and a predetermined gap is provided between the outer diameters of the first and second ferrules and the inner diameter of a hollow portion of the sleeve.

Description

Technical Field

[0001] The present invention mainly relates to an optical coupling unit used for switching the path of an optical line using a single-mode optical fiber in an optical fiber network, and an optical switch using the same.

Background Art

[0002] For all-optical switches that switch the path of light as light, various methods have been proposed as shown in Non-Patent Document 1, for example. Among these, although an optical fiber type mechanical optical switch that controls the butting of optical fibers or optical connectors with a robot arm, a motor, etc. is inferior to other methods in terms of slow switching speed, it has many excellent points compared to other methods in terms of low loss, low wavelength dependence, multi-portability, and having a self-holding function that holds the switching state when the power supply is lost. As a typical structure, for example, a method of parallelly moving a stage using an optical fiber V-groove, a method of selectively coupling a plurality of optical fibers that are emitted from an incident optical fiber by parallelly moving or changing the angle of a mirror or a prism, a method of connecting a jumper cable with an optical connector using a robot arm, etc. are available.

[0003] In addition, a method using a multi-core fiber has been proposed as an optical path for switching. For example, by combining a 3D MEMS optical switch with a multi-core fiber (see Non-Patent Document 2, for example), it becomes possible to switch multiple paths at once. Further, by rotating a cylindrical ferrule in which a multi-core fiber is inserted (see Patent Document 1, for example), optical components such as lenses and prisms are not required, and the configuration can be simplified.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005] [Non-Patent Document 1] M. Ctepanovsky, “A Comparative Review of MEMS-Based Optical Cross-Connects for All-Optical Networks From the Past to the Present Day,” IEEE Communications Surveys & Tutorials, vol.21, no.3, pp.2928 - 2946, 2019. [Non-Patent Document 2] K. Hiruma, T. Sugawara, K. Tanaka, E. Nomoto, and Y. Lee, “Proposal of High-capacity and High-reliability Optical Switch Equipmet with Multi-core Fibers,” 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching (OECC / PS), ThT1-2, 2013. [Non-Patent Document 3] B. Jian, “The Non-Contact Connector: A New Category of Optical Fiber Connector,” 2015 Optical Fiber Communications Conference and Exhibition (OFC), W2A.1, 2015. [Non-Patent Document 4] Hajime Araki, Akira Yakaabe, Shinya Uehara, Daisuke Sasaki, Takayuki Shimazu, “Dust-resistant Optical Multi-core Connector FlexAirConnecT Featuring Low Loss / Low Insertion Force,” July 2018, SEI Technical Review, No.193, pp.26 - 31, 2018. [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in the prior art described in the above-mentioned Non-Patent Document 1, there is a problem that further power reduction, miniaturization, and cost reduction are difficult. Specifically, in the method of parallelly moving the above-mentioned optical fiber V-groove stage or prism, generally a motor is used as a drive source. However, due to the mechanism for linearly moving heavy objects such as stages, a certain amount of torque or more is required for the motor, and power consumption is required to obtain an appropriate output to maintain the required torque. In addition, for optical axis alignment using a single-mode optical fiber, since an accuracy of about 1 μm or less is required, in a mechanism for converting the rotational motion of the motor into a linear motion (generally a ball screw is used), it is necessary to convert it into a linear motion with a sub-μm step. Considering that the optical fiber pitch of the usually used output-side optical fiber array is about 125 μm of the cladding outer diameter of the optical fiber or about 250 μm of the coating outer diameter of the optical fiber, the longer the actual driving time of the motor becomes as the output-side optical fiber array becomes larger, and there is a problem that the power consumption increases. For this reason, generally, such an optical fiber type mechanical optical switch requires power of several hundred mW or more. In addition, the robot arm method using an optical connector has a problem that a large amount of power of several tens of W or more is required for the robot arm itself that controls the insertion and extraction of the optical connector or ferrule.

[0007] In addition, in the optical path switching using a multi-core fiber described in Non-Patent Document 2, in the process of manufacturing the optical switch, a collimating mechanism for coupling to the output-side optical fiber array and a vibration isolation mechanism for obtaining stable optical characteristics against external factors such as vibration are separately required, and there is a problem that the assembly process becomes complicated.

[0008] In the optical path switching using a cylindrical ferrule into which the multi-core fiber described in Patent Document 1 is inserted, the ferrule is inserted into the sleeve in close contact to align the central axis of the ferrule. Due to the frictional force between the ferrule and the sleeve, a large amount of energy is required to drive the rotation, resulting in a large power consumption problem. Furthermore, when the ferrule rotates, in order to prevent damage to the opposing fiber end faces and deterioration of optical characteristics such as connection loss, a mechanism is required to separate the ferrule end face every time the ferrule rotates, resulting in an additional energy requirement for driving the rotation problem.

[0009] On the other hand, in a cylindrical ferrule into which an optical fiber is inserted, there is also a method of preventing damage to the fiber end face due to contact by a connection form (for example, Non-Patent Document 3) in which a gap is provided in advance and fiber contact is not made. However, in order to suppress signal deterioration due to reflection caused by the air layer generated between the fiber end faces due to the gap, a special coating for preventing reflection is required, resulting in an increase in cost problem.

[0010] Also, as another method for preventing reflection, there is a method of polishing the ferrule end face obliquely (for example, Non-Patent Document 4). However, in the obliquely polished ferrule, interference of the ferrule end face occurs during switching due to rotation, or a large connection loss occurs due to the requirement of a large gap problem.

[0011] In order to solve the above problems, an object of the present invention is to provide an optical coupling portion and an optical switch that can realize stable optical characteristics against external factors with low power consumption and more economically.

Means for Solving the Problems

[0012] To achieve the above object, in the optical coupling part and the optical switch of the present disclosure, the end faces of two ferrules in which single-core fibers are arranged parallel to the ferrule central axis and at the same distance from the ferrule central axis are convex spherical surfaces, and the tips of the end faces of the two ferrules are abutted so that the ferrule central axes coincide, and one of the ferrules is rotated about the ferrule central axis.

[0013] Specifically, the optical coupling part according to the present disclosure A first ferrule having one or more single-core fiber core centers arranged on the same circumference from the center in the ferrule cross-section, and having an end face that is convex spherical in the ferrule central axis direction together with the end face of the single-core fiber; A second ferrule having a plurality of single-core fiber core centers arranged on a circumference having the same diameter as the circumference on which the single-core fiber core center in the first ferrule is arranged from the center in the ferrule cross-section, and having an end face that is convex spherical in the ferrule central axis direction together with the end face of the single-core fiber; The first ferrule and the second ferrule have a hollow portion into which the first ferrule and the second ferrule are inserted so that the ferrule central axes of the first ferrule and the second ferrule coincide and the convex spherical end faces face each other, and a cylindrical sleeve provided with a predetermined gap between the outer diameters of the first ferrule and the second ferrule and the inner diameter of the hollow portion so that the first ferrule and the second ferrule can rotate; Comprising.

[0014] For example, in the optical coupling part according to the present disclosure In each of the first ferrule and the second ferrule, the angle formed by the cross-section perpendicular to the ferrule central axis and the end face of the single-core fiber may be 4.5 degrees or more.

[0015] For example, in the optical coupling part according to the present disclosure The gap between the end face of the single-core fiber of the first ferrule and the end face of the single-core fiber of the second ferrule whose optical axis coincides with that of the single-core fiber may be 22 μm or less.

[0016] For example, the optical coupling part according to the present disclosure The distance from the ferrule center of the core center of each single-core fiber in the first ferrule and the second ferrule may be 250 μm or less.

[0017] For example, the optical coupling part according to the present disclosure In each of the first ferrule and the second ferrule The radius of curvature in the convex spherical shape may be from 0.5 mm to 3.2 mm.

[0018] Specifically, the optical switch according to the present disclosure The optical coupling part and A rotation mechanism for rotating either the first ferrule or the second ferrule of the optical coupling part about the ferrule central axis, and comprises.

[0019] For example, the optical switch according to the present disclosure An actuator for rotating the rotation mechanism in a fixed angle step and stopping it at an arbitrary angle step, and A bearing constituting the rotation mechanism, and May further comprise.

[0020] In the present invention, the end faces of two ferrules in which a single-core fiber is arranged parallel to the ferrule central axis and at the same distance from the ferrule central axis have a convex spherical shape. The tips of the end faces of the two ferrules are butted so that the ferrule central axes coincide, and by rotating either one of the ferrules about the ferrule central axis, the end faces of the opposing optical fibers do not contact each other, and deterioration of optical characteristics such as connection loss due to scratches on the end faces of the optical fibers caused by contact can be prevented. Further, by making the end faces of the opposing optical fibers non-parallel, the amount of light reflection can be reduced, so that a reflection coating is not required, and a more economical optical coupling part and optical switch can be provided.

[0021] Furthermore, in the present invention, since one of the input side and the output side of the optical coupling part that performs optical switching is a mechanism capable of axial rotation, the energy required by the actuator, that is, the torque output, can be made as small as possible, and low power consumption can be achieved. In addition, the amount of optical axis deviation in a direction other than the axial rotation of the input-side ferrule is guaranteed by the sleeve in the optical coupling part, so that low loss can be achieved. In addition, the present invention does not include a collimator or a special anti-vibration mechanism, and is composed of generally widely used optical connection components such as ferrules and sleeves, so it is small and economical.

[0022] Note that the above inventions can be combined as much as possible.

Effects of the Invention

[0023] According to the present disclosure, it is possible to provide an optical coupling part and an optical switch that can realize stable optical characteristics against external factors with low power consumption and more economically.

Brief Description of the Drawings

[0024]

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Mode for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments shown below. These examples are merely illustrative, and the present disclosure can be implemented in various modified forms based on the knowledge of those skilled in the art. In the present specification and drawings, components having the same reference numerals indicate the same components as each other.

[0026] (Embodiment 1) FIG. 1 is a diagram showing an example of an embodiment of the present invention. In this embodiment, a form in which light is incident from the input-side optical fiber S01 and exits to the output-side optical fiber S04 will be described, but the direction of the light may be reversed. In the present invention, the input-side optical fiber S01 connected to the front-stage optical switch component S00 is switched to a specific port of the inter-optical-switch optical fiber S02 in the front-stage optical switch component S00, and the port of the inter-optical-switch optical fiber S02 is switched to a desired output-side optical fiber S04 in the rear-stage optical switch component S03. The present invention is an optical switch corresponding to the front-stage optical switch component S00 and the rear-stage optical switch component S03. Hereinafter, the front-stage optical switch component S00 is abbreviated as the optical switch S00, and the rear-stage optical switch component S03 is abbreviated as the optical switch S03. Since the optical switch S00 and the optical switch S03 are in a relationship of left-right inversion and have the same configuration, the detailed configuration will be shown using the optical switch S00 hereinafter.

[0027] FIG. 2 is a block configuration diagram according to an embodiment of the present invention. The optical coupling part S8 included in the optical switch S00 according to this embodiment is a first ferrule having, on the same circumference from the center in the ferrule cross section, the core centers of one or more single-core fibers arranged, and having an end face that is convex spherical in the ferrule central axis direction, together with the end face of the single-core fiber. In the ferrule cross-section, the core centers of a plurality of single-core fibers are arranged on a circumference having the same diameter as the circumference on which the core center of the single-core fiber in the first ferrule is arranged, from the center. Together with the end face of the single-core fiber, there is a second ferrule having an end face that is convex spherical in the ferrule central axis direction. The ferrule central axes of the first ferrule and the second ferrule coincide, and there is a hollow portion into which the first ferrule and the second ferrule are inserted so that the convex spherical end faces face each other. A cylindrical sleeve S17 is provided with a predetermined gap between the outer diameters of the first ferrule and the second ferrule and the inner diameter of the hollow portion so that the first ferrule and the second ferrule can rotate. In FIG. 2, the input-side optical fiber S1 has a configuration consisting of one single-core fiber, and the input-side ferrule S6 is the first ferrule. Also, the output-side optical fiber S9 has a configuration consisting of a plurality of single-core fibers, and the output-side ferrule S7 is the second ferrule. Note that the input-side optical fiber S1 corresponds to the input-side optical fiber S01 in FIG. 1, and the output-side optical fiber S9 corresponds to the inter-optical switch optical fiber S02 in FIG. 1. Also, hereinafter, the "end face of the single-core fiber" will be abbreviated as the "single-core fiber end face".

[0028] The optical switch S00 shown in Fig. 2 has an optical coupling section S8 composed of an input-side ferrule S6 into which the input-side optical fiber S1 is inserted and an output-side ferrule S7 into which the output-side optical fiber S9 is inserted. When light is incident from the input-side optical fiber S1, by fixing the output-side ferrule S7 and rotating the input-side ferrule S6, the input-side optical fiber S1 can be connected to any one core of the output-side optical fiber S9, and the incident light can be output from one core of the output-side optical fiber S9. It is an optical switch S00 that can be used as a 1×N relay-type optical switch. Conversely, it is also possible to make light incident from the output-side optical fiber S9. For example, light is made incident on a plurality of single-core fibers among the output-side optical fibers S9, the output-side ferrule S7 is fixed, and the input-side ferrule S6 is rotated to connect any one core of the output-side optical fiber S9 to the input-side optical fiber S1, and only one selected from the plurality of incident lights can be output from the input-side optical fiber S1. Also, as shown in Fig. 1, it is possible to configure an N×N optical switch by combining a plurality of optical switches. Here, although the output-side ferrule S7 is fixed and the input-side ferrule S6 is rotated, any one of the input-side ferrule S6 or the output-side ferrule S7 may be fixed and the opposite side may be rotated to enable switching of the opposing fibers. Therefore, the input-side ferrule S6 may be fixed and the output-side ferrule S7 may be rotated. Also, although the input-side ferrule S6 has one core, it is also possible to arrange a plurality of optical fibers.

[0029] The optical switch S00 that fixes the output-side ferrule S7 and rotates the input-side ferrule S6 will be described below. The output-side ferrule S7 is fixed by a rotation prevention mechanism (not shown) so as not to rotate about the axis. The actuator S3 rotates at an arbitrary angle according to a signal from the control circuit S4. The input-side ferrule S6 rotates when the output of the actuator S3 is transmitted through the rotation mechanism S5. In addition, the input-side ferrule S6 is provided with a certain amount of slack S2 for allowing the twist of the input-side optical fiber S1. Further, the optical coupling section S8 is configured to suppress axial displacement by an axial displacement adjustment mechanism (not shown) and avoid excessive loss due to axial displacement.

[0030] FIG. 3 is a schematic diagram showing the end face of the input-side ferrule S6 according to an embodiment of the present invention as viewed from the front. As shown in FIG. 3, the core center of the input-side optical fiber S1 is arranged on the circumference of a circle with a core arrangement radius Rcore with respect to the center of the input-side ferrule S6. In FIG. 3, an example is given in which a single-core input-side optical fiber S1 is arranged on the y-axis (x = 0), but the core center of the input-side optical fiber S1 may be arranged on the circumference of a circle having a core arrangement radius Rcore, and is not limited thereto.

[0031] FIG. 4 is a schematic diagram showing the end face of the output-side ferrule S7 according to an embodiment of the present invention as viewed from the front. As shown in the figure, the core centers of the plurality of output-side optical fibers S9 are arranged on the circumference of a circle with a core arrangement radius Rcore with respect to the center of the output-side ferrule S7. In FIG. 4, an example is given in which a total of eight output-side optical fibers S9 are arranged, but the core centers of the plurality of output-side optical fibers S9 may be arranged on the circumference of a circle having a core arrangement radius Rcore, and is not limited thereto.

[0032] It is important to minimize the transmission loss of the optical coupling section S8. It is desirable that each core of the output-side optical fiber S9 has the same optical characteristics in terms of having a mode field diameter similar to that of the core of the input-side optical fiber S1. Also, it is important to minimize the excess loss due to axial misalignment. It is desirable that the ferrule outer diameter S15 of the output-side ferrule S7 is approximately the same as the ferrule outer diameter S15 of the input-side ferrule S6.

[0033] In this embodiment, the input-side ferrule S6 and the output-side ferrule S7 are made of zirconia, and the input-side optical fiber S1 and the output-side optical fiber S9 are made of silica glass. However, any optical fiber capable of communicating signal light in the communication wavelength band may be used, and it is not limited to this.

[0034] FIG. 5 is a schematic diagram showing the optical coupling section S8 according to an embodiment of the present invention in a plane along the longitudinal direction. The input-side ferrule S6 into which the input-side optical fiber S1 is inserted and the output-side ferrule S7 into which the output-side optical fiber S9 is inserted are centered by a cylindrical sleeve S17 having an inner diameter S16 that is slightly larger by about sub-μm with respect to their ferrule outer diameters S15. A slight clearance C of about sub-μm is provided for the input-side ferrule S6 and the output-side ferrule S7 to control the axial misalignment within a certain allowable range and not to prevent the axial rotation of the input-side ferrule S6.

[0035] FIG. 6 is a diagram showing an example of the relationship between the excess loss T C and the clearance C between the ferrule outer diameter S15 of the input-side ferrule S6 and the output-side ferrule S7 and the sleeve inner diameter S16. In the optical coupling between optical fibers, the axial misalignment of the fiber cores is a cause of excess loss. Since the increase in excess loss is a factor that limits the total length of the optical path, it is necessary to reduce the axial misalignment of the fiber cores. Here, since the clearance C between the ferrule outer diameter S15 and the sleeve inner diameter S16 corresponds to the axial misalignment of the fiber cores, the relationship between the clearance C (unit: μm) between the ferrule outer diameter S15 and the sleeve inner diameter S16 and the excess loss T C (unit: dB) can be expressed by Equation (1).

Number

[0036] FIG. 7 is a schematic diagram showing in more detail the vicinity of the end of the ferrule of the optical coupling section S8 according to the embodiment of the present invention. The end faces of the input-side ferrule S6 and the output-side ferrule S7 are convex spherical surfaces in the ferrule central axis direction. The tips of the input-side ferrule S6 and the output-side ferrule S7 are butted against each other. The input-side optical fiber S1 and the output-side optical fiber S9 are arranged at the position of the core arrangement radius Rcore in the ferrule cross section as described above. The end faces of the input-side optical fiber S1 and the output-side optical fiber S9 are recessed from the tips in order to prevent the end faces from contacting and being damaged during switching by rotation. Also, at the end faces of the input-side optical fiber S1 and the output-side optical fiber S9, the angle θ formed by the cross section perpendicular to the ferrule central axis and the single-core fiber end face is controlled in order to suppress signal characteristic degradation due to reflection.

[0037] FIG. 8 is a diagram showing an example of the relationship between the angle θ formed by the cross-section perpendicular to the ferrule central axis and the single-core fiber end face and the reflection attenuation amount R. In the optical coupling section S8, if there is a region with a different refractive index between the end face of the input-side optical fiber S1 and the end face of the output-side optical fiber S9, the signal characteristics deteriorate due to reflection. In the configuration of the present invention shown in FIG. 7, there is a gap G between the end face of the input-side optical fiber S1 and the end face of the output-side optical fiber S9. Since the refractive indices of quartz glass and air are different, a measure for reducing reflection is necessary. In the present invention, reflection is reduced by controlling the angle θ. The relationship between the angle θ (unit: degree) formed by the cross-section perpendicular to the ferrule central axis and the single-core fiber end face and the reflection attenuation amount R (unit: dB) can be expressed by Equation 2.

Equation

Equation

[0038] FIG. 9 is a diagram showing an example of the relationship between the excess loss T G and the gap G. In the optical coupling between the input-side optical fiber S1 and the output-side optical fiber S9, if there is a gap G between the end face of the input-side optical fiber S1 and the end face of the output-side optical fiber S9, the distribution of the light emitted from the input-side optical fiber S1 spreads, and the coupling efficiency with the core of the output-side optical fiber S9 decreases, which becomes a factor of excess loss. The gap G (unit: μm) and the excess loss T GThe relationship of (unit: dB) can be expressed by Equation 4.

Equation

[0039] FIG. 10 is a diagram showing an example of the relationship between the curvature radius Rcur of the ferrule end face with a convex spherical shape and the angle θ formed between the cross section perpendicular to the ferrule central axis and the single-core fiber end face. The relationship between the curvature radius Rcur (unit: mm) of the ferrule end face with a convex spherical shape and the angle θ (unit: degree) formed between the cross section perpendicular to the ferrule central axis and the single-core fiber end face can be expressed by Equation 5 using the core arrangement radius Rcore (unit: μm).

Equation

[0040] Fig. 11 is a diagram showing an example of the relationship between the distance D from the ferrule tip to the single-core fiber end face with respect to the curvature radius Rcur of the ferrule end face having a convex spherical shape. The distance D from the ferrule tip to the single-core fiber end face corresponds to half of the gap G between the end faces of the input-side optical fiber S1 and the output-side optical fiber S9, and can be expressed by Equation (6) using the curvature radius Rcur (unit: mm) of the ferrule end face having a convex spherical shape and the angle θ (unit: degree) formed by the cross-section perpendicular to the ferrule central axis and the single-core fiber end face.

Equation

[0041] In order for the optical coupling portion S8 of the optical switch S00 according to this embodiment to obtain a reflection attenuation amount of 40 dB or more and an excess loss due to a gap of 0.1 dB or less, in each of the input-side ferrule S6 and the output-side ferrule S7, the curvature radius in the convex spherical shape may be from 0.5 mm to 3.2 mm.

[0042] Next, requirements related to the actuator S3 in FIG. 2, the input-side ferrule S6 described in FIG. 3, and the output-side ferrule S7 described in FIG. 4 will be described. The actuator S3 has a drive mechanism that rotates in arbitrary angular steps by a pulse signal from the control circuit S4 and has a constant holding torque for each angular step. For example, a stepping motor is used. Note that the actuator S3 may use other methods as long as it has a drive mechanism that rotates in arbitrary angular steps by a pulse signal from the control circuit S4 and has a constant holding torque for each angular step. The rotation speed and rotation angle are determined by the period and number of pulses of the pulse signal from the control circuit S4, and the angular step and holding torque may be adjusted via a reduction gear. As described above, since the input-side ferrule S6 in the optical coupling unit S8 is designed to rotate about the axis, it has the characteristic that the holding torque required to hold the rotation angle of the input-side ferrule S6 is applied by the actuator S3.

[0043] Thereby, it has a self-holding function that does not require power during stationary state after switching, and it is possible to make the driving energy when switching the optical path as small as possible, and it is possible to provide an optical switch with low power consumption.

[0044] Here, in the stepping motor, if the number of angular steps at which the angular position is held when the power supply is stopped is defined as the holding angular step number, the holding angular step number is a natural number multiple of the number of cores having the same core arrangement radius Rcore of the output-side optical fiber S9.

[0045] Also, the excess loss due to the rotation angle deviation in the optical coupling unit S8 is T R (unit: dB), the rotation angle deviation related to the holding angle accuracy of the stepping motor is Φ (unit: °), the core arrangement radius is Rcore (unit: μm), and the mode field radii of the cores of the input-side optical fiber S1 and the output-side optical fiber S9 are ω1 and ω2 (unit: μm), respectively. These relationships can be expressed by Equation 7.

Equation

[0046] FIG. 13 is a schematic diagram showing an example of the fitting form of the optical coupling portion S8 according to the first embodiment of the present invention. The output-side ferrule S7 is attached to the output-side flange S19 with a notch, and the output-side flange 19 is attached to the fixing jig S27 with the fixing screw S25, and the axial direction and the axial rotation direction are fixed. The input-side ferrule S6 is attached to the rotating flange S29, and a bearing S26 is provided on the rotating flange S29. Similarly, it is also attached to the fixing jig S27 with the fixing screw S25, and the axial direction is fixed. A sleeve S17 is built into the fixing jig S27, and the input-side ferrule S6 and the output-side ferrule S7 are axially aligned by being inserted into the sleeve S17. The output-side ferrule S7 is fixed, and the input-side ferrule S6 rotates within the sleeve S17 by the rotation mechanism S5 of the bearing S26 around the center of the ferrule cylinder. As a result, the core of the input-side optical fiber S1 inserted into the input-side ferrule S6 rotates, and the core of the output-side optical fiber S9 facing the input-side optical fiber S1 is switched. Note that, for example, zirconia is used for the bearing S26, but other materials can also be used as long as they can be manufactured with high dimensional accuracy. Further, by forming the fixing jig S27, for example, as a frame made of a metal with low rigidity and a hollow shape, it is possible to reduce the axial displacement of the input-side ferrule S6 due to the axial vibration during the rotation of the actuator. FIG. 17 shows a cross-sectional view of the notched output-side flange S19 attached to the output-side ferrule S7, cut along a plane perpendicular to the axis in the longitudinal direction of the output-side flange S19. As shown in FIG. 17, a plurality of capillaries S23 may be inserted into the inside of each flange of the output-side flange S19. FIG. 18 shows a side view of the notched output-side flange S19 attached to the output-side ferrule S7. As shown in FIG. 18, the capillaries S23 are arranged at positions where the fiber holes S30 of the output-side ferrule S7 attached to the output-side flange S19 coincide with the central axis, respectively, so that it becomes easy to insert the output-side optical fiber S9 into the output-side ferrule S7.Furthermore, as shown in FIG. 18, by tapering the capillary S23 in the longitudinal direction and making the diameter of its tip approach the diameter of the fiber hole S30 of the output-side ferrule S7, when inserting the output-side optical fiber S9 into the output-side ferrule S7, it is possible to prevent snagging due to a step, and furthermore, to prevent breakage of the optical fiber. The same applies to the rotary flange S29 attached to the input-side ferrule S6. In this embodiment, an example of inserting a plurality of capillaries inside the flange is shown, but the shape inside the flange only needs to be a shape that allows the optical fiber to be inserted into the fiber hole and that can protect the optical fiber during the production of the optical coupling portion, and is not limited to this.

[0047] In the present invention, the end faces of two ferrules in which single-core fibers are arranged parallel to the ferrule central axis and at the same distance from the ferrule central axis are convex, and the tips of the end faces of the two ferrules are butted so that the ferrule central axes coincide. By rotating one of the ferrules about the ferrule central axis, the end faces of the opposing optical fibers do not come into contact with each other, and it is possible to prevent deterioration of optical characteristics such as connection loss caused by scratches on the end faces of the optical fibers due to contact. Further, by making the end faces of the opposing optical fibers non-parallel, the amount of light reflection can be reduced, so that a reflection coating is not required, and a more economical optical coupling portion and optical switch can be provided.

[0048] Furthermore, in the present invention, since one of the input side and the output side of the optical coupling portion S8 that performs optical switching is a mechanism that can rotate about an axis, the energy required by the actuator S3, that is, the torque output, can be made infinitely small, and low power consumption can be achieved. In addition, since the amount of optical axis deviation in a direction other than the axis rotation of the input-side ferrule S6 is guaranteed by the sleeve S17 in the optical coupling portion S8, low loss can be achieved. In addition, the present invention does not include a collimator or a special anti-vibration mechanism, and is composed of generally widely used optical connection components such as ferrules and sleeves, so it is small and economical.

[0049] Therefore, according to the present invention, it is possible to provide an optical coupling section and an optical switch that can realize stable optical characteristics against external factors such as temperature and vibration with low power consumption and more economically. As a result, in an optical path using a single-mode optical fiber of an optical fiber network, it can be used for an optical switch that switches a path in any facility regardless of location.

[0050] (Embodiment 2) Hereinafter, the configuration and operation of the optical switch S00 according to the present embodiment will be specifically described with reference to FIGS. 14 and 15. In the optical switch S00 of the present embodiment, the input-side ferrule S6 of the optical coupling section S8 is attached to the input-side flange S18 instead of the rotary flange S29, and the position where the bearing S26 is provided is different from that of the optical switch S00 in the first embodiment. Hereinafter, the rotation mechanism of the input-side ferrule S6 will be described. Note that, except for the content described below, it is the same as that in the first embodiment.

[0051] FIG. 14 is a schematic diagram showing the fitting form of the optical coupling section S8 according to the present embodiment. Similar to the first embodiment, the output-side ferrule S7 is attached to the output-side flange S19 with a notch, and the output-side flange S19 is attached to the fixing jig S27 with the fixing screw S25, and the axial direction and the axial rotation direction are fixed.

[0052] The input-side ferrule S6 is attached to the input-side flange S18 with a notch. The input-side flange S18 is attached to the fixing jig S27 with removable fixing screws S25, and the axial direction and the axial rotation direction are fixed. By loosening the fixing screws S25, the input-side flange S18 can rotate, and accordingly, the input-side ferrule S6 attached to the input-side flange S18 can rotate. Also, as will be described later, the input-side flange S18 may have the structure shown in FIG. 15. At this time, fixing screws (not shown) for fixing the axial direction may be provided separately. The input-side ferrule S6 has a smaller ferrule outer diameter S15 than the output-side ferrule S7, and a bearing S26 is attached thereto and rotates by the rotation mechanism S5 of the bearing S26. That is, when the output-side ferrule S7 is fixed and the input-side flange S18 can rotate, the input-side ferrule S6 rotates within the sleeve S17 about the center of the ferrule cylinder by the rotation mechanism S5 of the bearing S26. As a result, the core of the input-side optical fiber S1 inserted into the input-side ferrule S6 rotates, and the core of the output-side optical fiber S9 opposing the input-side optical fiber S1 is switched.

[0053] FIG. 15 is a schematic diagram showing a cross section of the input-side ferrule S6 of the optical coupling section S8 according to the present embodiment. A bearing S26 is attached around the input-side ferrule S6 so that the input-side ferrule S6 can rotate freely within the sleeve S17. Further, FIG. 15 shows an example in which a fixing spring S28 is used as a method for fixing the input-side flange S18. A groove as shown in FIG. 15 is provided in advance in the input-side flange S18, and the input-side flange S18 and the input-side ferrule S6 fixed thereto are fixed by sandwiching the tip of the fixing spring S28 in the groove. By applying a force to the fixing spring S28 in the direction of the arrow, the fixing of the input-side ferrule S6 is released and it can rotate. For example, by interlocking the fixing and release of this fixing spring S28 with a control circuit S4 (not shown) that controls the actuator S3, batch control of optical fiber switching becomes possible. Further, as shown in FIG. 16, by forming the outer peripheral shape of the input-side flange S18 into a shape in which a plurality of gears are arranged so that the grooves are displaced along the longitudinal direction of the input-side ferrule S6, it is also possible to perform more detailed rotation angle control. Further, as a method for fixing and releasing the input-side flange S18, a magnet or a solenoid may be used in addition to the fixing spring S28.

[0054] As described above, according to the present invention, it is possible to provide an optical coupling section and an optical switch that can realize stable optical characteristics against external factors with low power consumption and more economically.

[0055] Note that the above inventions can be combined as much as possible.

Industrial Applicability

[0056] The optical coupling section and the optical switch according to the present disclosure can be applied to the optical communication industry.

Explanation of Signs

[0057] S00: Front-stage optical switch component S00: Optical switch S01: Input-side optical fiber S02: Optical fiber between optical switches S03: Rear-stage optical switch component S03: Optical switch S04: Output-side optical fiber S1: Input-side optical fiber S2: Slack portion S3: Actuator S4: Control circuit S5: Rotation mechanism S6: Input-side ferrule S7: Output-side ferrule S8: Optical coupling section S9: Output-side optical fiber S15: Ferrule outer diameter S16: Sleeve inner diameter S17: Sleeve S18: Input-side flange S19: Output-side flange S23: Capillary S25: Fixing screw S26: Bearing S27: Fixing jig S28: Fixing spring S29: Rotating flange S30: Fiber hole

Claims

1. In the ferrule cross-section, the core centers of one or more single-core fibers are arranged on the same circumference from the center, and together with the end faces of the single-core fibers, a first ferrule having an end face that is a convex spherical shape in the ferrule central axis direction, In the ferrule cross-section, from the center, the core centers of a plurality of single-core fibers are arranged on the same circumference as the circumference on which the core center of the single-core fiber in the first ferrule is arranged, and together with the end faces of the single-core fibers, a second ferrule having an end face that is a convex spherical shape in the ferrule central axis direction, A cylindrical sleeve having a hollow portion into which the first ferrule and the second ferrule are inserted such that the ferrule central axes of the first ferrule and the second ferrule coincide and the convex spherical end faces face each other, and a predetermined gap is provided between the outer diameters of the first ferrule and the second ferrule and the inner diameter of the hollow portion so that the first ferrule and the second ferrule can rotate, An optical coupling portion comprising: An optical coupling portion characterized in that the end faces of the first ferrule and the second ferrule are abutted against each other at the tips having the convex spherical shape within the sleeve.

2. In each of the first ferrule and the second ferrule, the angle formed by the cross-section perpendicular to the ferrule central axis and the end face of the single-core fiber is 4.5 degrees or more The optical coupling portion according to claim 1, characterized in that.

3. The gap between the end face of the single-core fiber of the first ferrule and the end face of the single-core fiber of the second ferrule whose optical axis coincides with that of the single-core fiber is 22 μm or less The optical coupling portion according to claim 1, characterized in that.

4. The distance of the core center of each single-core fiber in the first ferrule and the second ferrule from the ferrule center is 250 μm or less The optical coupling portion according to claim 1, characterized in that.

5. In each of the first ferrule and the second ferrule, The radius of curvature in the convex spherical shape is from 0.5 mm to 3.2 mm The optical coupling portion according to claim 1, characterized in that.

6. The optical coupling portion according to claim 1, and A rotation mechanism that rotates either one of the first ferrule and the second ferrule of the optical coupling portion about the ferrule central axis. An optical switch characterized by this. **Claim 7** An actuator that rotates the rotation mechanism in a fixed angle step and stops it at an arbitrary angle step. A bearing that constitutes the rotation mechanism. The optical switch according to claim 6, further comprising this.

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