Optical connection device and optical switch using the same

Abstract

The purpose of the present invention is to make it possible to realize, at low cost, an optical switch whereby optical characteristics that are stable against external factors can be driven with low power consumption.　The present invention is an optical connection device for connecting a first ferrule and a second ferrule, the optical connection device being characterized by comprising a cylindrical sleeve into which a first ferrule and a second ferrule are inserted, a spring for causing a distal-end part of the first ferrule and a distal-end part of the second ferrule to abut each other, and a holder for holding the first ferrule, the second ferrule, the cylindrical sleeve, and the spring, and the first ferrule or the second ferrule can move in an arbitrary direction perpendicular to a center axis inside the holder and is held in the holder so as not to rotate about the center axis.

Description

[Technical field]

[0001] The present disclosure relates to an optical connection device used mainly 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 technology]

[0002] Various methods have been proposed as all-optical switches that switch the path of light while keeping it as light, as shown in, for example, Non-Patent Document 1. Among these, optical fiber mechanical optical switches, which use a motor or the like to control the butting of optical fibers or optical connectors, are inferior to other methods in terms of slow switching speed, but have many advantages over other methods, such as low loss, low wavelength dependency, multi-port capability, and a self-holding function that maintains the switched state when power is lost. Representative structures include, for example, a method in which a stage using an optical fiber V-groove is translated, and a method in which a mirror or prism is translated or the angle is changed to selectively couple an input optical fiber to multiple output optical fibers.

[0003] In addition, a method has been proposed in which switching is performed by rotating a cylindrical ferrule into which a multi-core fiber is inserted (see, for example, Patent Document 1), which eliminates the need for optical components such as lenses and prisms and makes it possible to simplify the optical switch configuration.

[0004] In the optical path switching described in Patent Document 1, in which a cylindrical ferrule into which a multi-core fiber is inserted is rotated by a motor to switch, the central axis of the ferrule is aligned by inserting it into a sleeve, and when the motor rotates, the rotation axis of the shaft moves horizontally and vertically, so that the rotation axis of the rotating ferrule also moves horizontally and vertically at the end face of the ferrule, which causes an excessive lateral pressure between the ferrule and the sleeve, increasing the frictional force, and requiring a large amount of energy and a large amount of power to drive the rotation. Furthermore, there is a problem that the ferrule or the sleeve is damaged when a large lateral pressure is applied. In addition, in order to prevent deterioration of optical characteristics such as connection loss by scratching the opposing fiber end faces when the ferrule rotates, a mechanism is required to separate the ferrule end faces every time the ferrule rotates, and there is a problem that extra energy is required to drive the rotation.

[0005] On the other hand, there is a method to prevent scratches on the fiber end face due to contact by providing a gap in advance in a cylindrical ferrule into which an optical fiber is inserted, and using a connection form that does not involve fiber contact (for example, Non-Patent Document 2). However, in order to suppress signal degradation due to reflection caused by an air layer that occurs between the fiber end faces due to the gap, a special coating to prevent reflection is required, which poses the problem of increased costs.

[0006] Another method for preventing reflection is to polish the ferrule end face at an angle (for example, Non-Patent Document 3). However, with a ferrule polished at an angle, there are problems such as interference of the ferrule end face during switching by rotation, or a large gap being required, resulting in large connection loss. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2-82212 [Non-patent literature]

[0008] [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,vоl.21,nо.3,pp.2928-2946,2019. [Non-Patent Document 2] 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 3] Hajime Arao, Sachi Yagabe, Fumiya Uehara, Dai Sasaki, Takayuki Shimazu, "FlexAirConnecT: A dust-resistant optical multi-fiber connector featuring low loss and low mating force," July 2018·SEI Technical Review, No. 193, pp. 26-31, 2018. Summary of the Invention [Problem to be solved by the invention]

[0009] In order to solve the above problems, an object of the present disclosure is to make it possible to realize, at low cost, an optical switch that has optical characteristics that are stable against external factors and can be driven with low power consumption. [Means for solving the problem]

[0010] The optical switch of the present disclosure comprises: An optical connecting device according to the present disclosure; and a rotation mechanism for rotating either the first ferrule or the second ferrule included in the optical connecting device about the central axis of the first ferrule or the second ferrule.

[0011] The optical connection device of the present disclosure includes: A first ferrule in which the core centers of one or more single-core fibers are arranged on the same circumference from the center in a cross section of the ferrule; a second ferrule in which 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, the circumference being located from the center in a cross section of the ferrule; and a cylindrical sleeve having a hollow portion into which the first ferrule and the second ferrule are inserted so that the central axes of the first ferrule and the second ferrule coincide, and a predetermined gap is provided between the outer diameter of each of the first ferrule and the second ferrule and the inner diameter of the hollow portion so that the first ferrule or the second ferrule can rotate.

[0012] The optical connecting device of the present disclosure realizes low power consumption of the optical switch by suppressing an increase in frictional force caused by wobbling of the rotation axis at the connecting portion between the first ferrule and the second ferrule.

[0013] Specifically, the optical connecting device of the present disclosure includes: a spring that applies pressure to a first flange of the first ferrule or a second flange of the second ferrule so as to butt a tip portion of the first ferrule against a tip portion of the second ferrule; a holder that holds the first ferrule, the second ferrule, the cylindrical sleeve, the first flange, the second flange, and the spring such that central axes of the first ferrule and the second ferrule are aligned, The first ferrule or the second ferrule is characterized in that it can move in any direction perpendicular to the central axis within the holder and is held by the holder so as not to rotate around the central axis. Effect of the Invention

[0014] According to the present disclosure, an optical switch that can operate with low power consumption and has stable optical characteristics against external factors can be provided at low cost by suppressing an increase in frictional force due to wobble of the rotation axis at the connection portion between the first ferrule and the second ferrule. [Brief description of the drawings]

[0015] [Figure 1] 1 shows an example of a usage form of an optical switch according to the present disclosure. [Diagram 2] 1 is a configuration diagram of an optical switch using an optical connecting device according to an embodiment of the present disclosure. [Diagram 3] 1 is a configuration diagram of an optical connecting device according to an embodiment of the present disclosure. [Figure 4] 1 is a schematic diagram showing an end portion of a fixed ferrule according to an embodiment of the present disclosure from the front. FIG. [Diagram 5] FIG. 2 is a schematic diagram showing an end portion of a rotating ferrule according to an embodiment of the present disclosure from the front. [Figure 6] 2 is a schematic diagram showing a ferrule and a cylindrical sleeve of an optical connecting device according to an embodiment of the present disclosure, taken along a longitudinal direction thereof; FIG. [Figure 7] 1 shows an example of the relationship between the excess loss and the clearance between the outer diameter of the ferrule and the inner diameter of the sleeve. [Figure 8] 4 is a schematic diagram showing in more detail the vicinity of an end portion of a ferrule of the optical connecting device according to an embodiment of the present disclosure. FIG. [Figure 9] 13 shows an example of the relationship between the angle between the tip portion and the annular portion and the return loss. [Figure 10] 1 shows an example of the relationship of excess loss to the gap of an optical fiber. [Figure 11] 1 shows an example of the relationship between the core arrangement radius and excess loss due to a rotation angle deviation. [Figure 12] 3 is a schematic diagram showing a cross section of the inside of a fixed-side flange holding portion according to the first embodiment of the present disclosure. FIG. [Figure 13] 11 is a schematic diagram showing a cross section of the inside of a fixed-side flange holding portion according to a second embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the 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 implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings are assumed to indicate the same components.

[0017] (Embodiment 1) 1 is a diagram illustrating an example of an embodiment of the present disclosure. The present disclosure makes it possible to switch an input side optical fiber S1 connected to a front-stage optical switch configuration unit S5 to a specific port of an inter-optical switch optical fiber S2 in the front-stage optical switch configuration unit S5, and to switch the port of the inter-optical switch optical fiber S2 to a desired output side optical fiber S4 in a rear-stage optical switch configuration unit S3.

[0018] The optical switch of the present disclosure is an optical switch corresponding to the front-stage optical switch component S5 and the rear-stage optical switch component S3. The optical switch of the present disclosure includes the optical connection device of the present disclosure. Hereinafter, the front-stage optical switch component S5 is abbreviated as the optical switch S5, and the rear-stage optical switch component S3 is abbreviated as the optical switch S3. In this embodiment, a form in which light is input from the input side optical fiber S1 and output to the output side optical fiber S4 is described, but the direction of the light may be reversed. The optical switch S5 and the optical switch S3 are in a left-right inverted relationship and have the same configuration, so the detailed configuration will be shown below using the optical switch S5.

[0019] 2 is a configuration diagram showing an example of an optical switch S5 using the optical connecting device disclosed herein. The optical switch includes, in order from the fixed-side optical fiber S8 side, a holder S7, a rotating-side flange S6, a rotating mechanism S10, and an actuator S11. The fixed-side optical fiber S8 corresponds to the input-side optical fiber S1 shown in FIG. 1, and the rotating-side optical fiber S9 corresponds to the inter-optical switch optical fiber S2 shown in FIG. 1.

[0020] The actuator S11 rotates at any angle in response to a signal from the control circuit S12. The rotating flange S6 rotates as the output of the actuator S11 is transmitted via the rotating mechanism S10. In order to transmit the rotational power directly to the rotating flange S6 in Fig. 2, the actuator S11 and the rotating mechanism S10 have a hollow structure, and the rotating optical fiber S9 can be passed through the hollow parts of the actuator S11 and the rotating mechanism S10.

[0021] For example, a motor is used as the actuator S11, and in this case, the rotation mechanism S10 is configured by the shaft of the motor. Although an example of a hollow actuator S11 and rotation mechanism S10 is shown in Fig. 2, a non-hollow actuator S11 and rotation mechanism S10 can also be used by installing a gear between the rotation side flange S6 and the rotation mechanism S10. A certain amount of extra length may be provided in the rotation side optical fiber S9 to allow twisting due to rotation.

[0022] 3 is a configuration diagram of an optical connection device according to an embodiment of the present disclosure. The optical connection device of the optical switch S5 according to this embodiment includes a fixed-side ferrule S13 to which a fixed-side flange (not shown) is attached, a rotating-side ferrule S14 to which a rotating-side flange S6 is attached, a cylindrical sleeve S15 into which the fixed-side ferrule S13 and the rotating-side ferrule S14 are inserted, and a spring S17, which are held by a holder S7 so that the central axes (symbol Ac shown in FIG. 8) of the fixed-side ferrule S13 and the rotating-side ferrule S14 are aligned.

[0023] The fixed-side flange holding portion S16 is slidable within the holder S7 in a direction in which the fixed-side ferrule S13 is pressed against the rotating-side ferrule S14, i.e., in a direction parallel to the central axis. The fixed-side flange holding portion S16 is also provided with a groove that engages with the flange-holding-portion fixing protrusion S18. By engaging the groove of the fixed-side flange holding portion S16 with the flange-holding-portion fixing protrusion S18, the fixed-side flange holding portion S16 is fixed to the holder S7 so as not to rotate about the central axes of the fixed-side ferrule S13 and the rotating-side ferrule S14.

[0024] The spring S17 applies pressure to an outer frame portion (reference symbol S27 described later) of the fixed side flange holding portion S16 so as to butt the tip portions of the fixed side ferrule S13 and the rotating side ferrule S14. The application of pressure by the spring S17 attached to the fixed side flange holding portion S16 causes the end faces of the fixed side ferrule S13 and the rotating side ferrule S14 to butt against each other. The rotating side ferrule S14 and the rotating side flange S6 may be provided with bearings or processed to reduce friction in order to reduce the driving force for rotation.

[0025] The fixed-side optical fiber S8 corresponds to the input-side optical fiber S1 in Fig. 1, and the rotating-side optical fiber S9 corresponds to the inter-optical switch optical fiber S2 in Fig. 1. When light is input from the fixed-side optical fiber S8, the fixed-side ferrule S13 is fixed, and by rotating the rotating-side ferrule S14, the fixed-side optical fiber S8 is connected to any one of the rotating-side optical fibers S9, and the input light can be output from one of the rotating-side optical fibers S9, and this optical switch can be used as a 1×N relay-type optical switch.

[0026] Conversely, it is also possible to input light from the rotation-side optical fiber S9. For example, light is input to a plurality of single-core fibers of the rotation-side optical fiber S9, and an arbitrary core of the rotation-side optical fiber S9 is connected to the fixed-side optical fiber S8 by rotating the rotation-side ferrule S14, so that only one light selected from the plurality of input light beams can be output from the fixed-side optical fiber S8.

[0027] Also, as shown in FIG. 1, it is possible to configure an N×N optical switch by combining a plurality of optical switches. Here, the fixed-side optical fiber S8 is one core, but it is also possible to arrange a plurality of optical fibers. Also, although the fixed-side optical fiber S8 is one core and the rotation-side optical fiber S9 is multiple cores, it is also possible to have the rotation-side optical fiber S9 be one core and the fixed-side optical fiber S8 be multiple cores. In this case, the fixed-side optical fiber S8 corresponds to the inter-switch optical fiber S2 in FIG. 1, and the rotation-side optical fiber S9 corresponds to the input-side optical fiber S1 in FIG. 1. Below, an optical switch S5 in which the fixed-side optical fiber S8 is one core and the rotation-side fiber S9 is multiple cores will be described.

[0028] 4 is a schematic diagram showing the end of the fixed-side ferrule S13 according to the embodiment of the present disclosure from the front. As shown in FIG. 4, the core center of the fixed-side optical fiber S8 is arranged on the circumference of a circle with a core arrangement radius Rcore relative to the center of the fixed-side ferrule S13.

[0029] 4 shows an example in which a single fixed-side optical fiber S8 is arranged on the y-axis (x=0), but this is not limiting as long as the core center of the fixed-side optical fiber S8 is arranged on the circumference of a circle having a core arrangement radius Rcore. Also, the fixed-side optical fiber S8 is arranged in an annular portion S20 of an annulus arranged outside the tip portion S19. Furthermore, the end face of the fixed-side optical fiber S8 is exposed to the annular portion S20.

[0030] FIG. 5 is a schematic diagram showing the end of the rotating-side ferrule S14 according to the embodiment of the present disclosure from the front. As shown in the figure, the core centers of the rotating-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 rotating-side ferrule S14. FIG. 5 shows an example in which a total of eight rotating-side optical fibers S9 are arranged, but the present invention is not limited to this as long as the core centers of the rotating-side optical fibers S9 are arranged on the circumference of a circle having a core arrangement radius Rcore. In addition, the rotating-side optical fiber S9 is arranged in the annular portion S20 of the annulus arranged outside the tip portion S19, similar to the fixed-side optical fiber S8. Furthermore, the end face of the rotating-side optical fiber S9 is exposed to the annular portion S20.

[0031] It is important to minimize the transmission loss in the connection between the fixed-side optical fiber S8 and the rotating-side optical fiber S9, and it is desirable that each core of the rotating-side optical fiber S9 has the same optical characteristics as the core of the fixed-side optical fiber S8 in that it has a mode field diameter similar to that of the core of the fixed-side optical fiber S8. It is also important to minimize the excess loss due to axial misalignment, and it is desirable that the ferrule outer diameter S21 of the rotating-side ferrule S14 is similar to the ferrule outer diameter S21 of the fixed-side ferrule S13.

[0032] In this embodiment, the fixed-side optical fiber S8 and the rotating-side optical fiber S9 are formed of quartz glass, but are not limited to this as long as they are optical fibers capable of communicating signal light in a communication wavelength band. Note that in this embodiment, an example is shown in which the tip portions S19 of the fixed-side ferrule S13 and the rotating-side ferrule S14 have flat surfaces, but the tip portions S19 do not need to be flat, and for example, one of the fixed-side ferrule S13 and the rotating-side ferrule S14 may be made convex and the other may be made concave so as to be in close contact with the convex shape.

[0033] 6 is a schematic diagram showing the ferrules and cylindrical sleeve of the optical connection device according to the embodiment of the present disclosure in a longitudinal plane. The cylindrical sleeve S15 has a hollow portion into which the fixed ferrule S13 and the rotating ferrule S14 are inserted. At this time, the fixed ferrule S13 and the rotating ferrule S14 are arranged so that their central axes Ac coincide with each other.

[0034] A predetermined gap is provided between the outer diameter of each of the fixed side ferrule S13 and the rotating side ferrule S14 and the inner diameter of the hollow portion so that the rotating side ferrule S14 can rotate around the central axis Ac. The fixed side ferrule S13 with the fixed side optical fiber S8 inserted therein and the rotating side ferrule S14 with the rotating side optical fiber S9 inserted therein are aligned with a cylindrical sleeve S15 having an inner diameter slightly larger than the outer diameter S23 of the ferrules by about sub-μm, and the axial misalignment is controlled within a certain tolerance range. In addition, a slight clearance C of about sub-μm is provided between the fixed side ferrule S13 and the rotating side ferrule S14 so as not to interfere with the axial rotation of the rotating side ferrule S14.

[0035] In addition, in order to butt the end faces of the fixed side ferrule S13 and the rotating side ferrule S14 together, the longitudinal length of the cylindrical sleeve S15 is set to be shorter than the combined longitudinal length of the fixed side ferrule S13 and the longitudinal length of the rotating side ferrule S14, i.e., the distance between the fixed side flange S22 and the rotating side flange S6.

[0036] 7 is a diagram showing an example of the relationship between the clearance C between the ferrule outer diameter S23 of the fixed ferrule S13 and the rotating ferrule S14 and the sleeve inner diameter S24 of the cylindrical sleeve S15 and the excess loss Tc. In optical coupling between optical fibers, the axial misalignment of the fiber cores is a cause of excess loss. Since an increase in excess loss limits the overall length of the optical path, it is necessary to reduce the axial misalignment of the fiber cores.

[0037] Since the clearance C between the ferrule outer diameter S23 and the sleeve inner diameter S24 corresponds to the axial misalignment of the fiber core, the relationship between the clearance C (unit: μm) between the ferrule outer diameter S23 and the sleeve inner diameter S24 and the excess loss Tc (unit: dB) can be expressed by the following equation 1.

number

[0038] 7 shows the loss when the mode field radii ω1 and ω2 of the cores of the fixed-side optical fiber S8 and the rotating-side optical fiber S9 are both 4.5 μm. For example, if the ferrule outer diameter S23 and the sleeve inner diameter S24 are processed so that the clearance C is 0.7 μm or less, the maximum excess loss can be suppressed to approximately 0.1 dB or less. In addition, if the maximum excess loss is set to 0.2 dB, it is necessary to process the ferrule outer diameter S23 and the sleeve inner diameter S24 so that the clearance C is 1 μm or less.

[0039] 8 is a schematic diagram showing in more detail the vicinity of the end of the ferrule of the optical connection device according to the embodiment of the present disclosure. The ends of the fixed-side ferrule S13 and the rotating-side ferrule S14 have a convex shape that protrudes toward the central axis Ac. The fixed-side ferrule S13 and the rotating-side ferrule S14 are butted against each other at their respective tip portions S19. FIG. 8 shows an example in which the tip portion S19 is a flat surface with a diameter Df perpendicular to the central axis Ac.

[0040] As described above, the fixed-side optical fiber S8 and the rotating-side optical fiber S9 are disposed in the annular portions S20 of the fixed-side ferrule S13 and the rotating-side ferrule S14, and have exposed end faces. The fixed-side optical fiber S8 and the rotating-side optical fiber S9 have end faces recessed from the tip portion S19 to prevent the end faces from coming into contact and being damaged when switching due to rotation.

[0041] In addition, in order to suppress deterioration of signal characteristics due to reflection at the end faces of the fixed-side optical fiber S8 and the rotation-side optical fiber S9, the angle θ between the tip portion S19 and the annular portion S20 is controlled. Note that in this embodiment, the end face of the annular portion S20 is formed linearly in the direction receding from the tip portion S19 in FIG. 8, but the annular portion S20 does not need to have a linear shape and may have a spherical shape, for example.

[0042] Fig. 9 is a diagram showing an example of the relationship between the angle θ of the annular portion S20 with respect to the tip portion S19 and the return loss R. In an optical connection device, if there is an area with a different refractive index between the end face of the fixed-side optical fiber S8 and the end face of the rotation-side optical fiber S9, signal characteristics will deteriorate due to reflection. In the configuration of the present disclosure shown in Fig. 8, there is a gap G between the end face of the fixed-side optical fiber S8 and the end face of the rotation-side optical fiber S9, and since silica glass and air have different refractive indices, some measure is required to reduce reflection. In the present disclosure, reflection is reduced by controlling the angle θ of the annular portion S20.

[0043] The relationship between the angle θ (unit: degree) of the annular portion S20 with respect to the tip portion S19 and the return loss R (unit: dB) can be expressed by the following equation 2.

number

[0044] Here, n1, ω1, and λ are the refractive index of the optical fiber, the mode field radius of the optical fiber core (unit: μm), and the wavelength of the propagating light in a vacuum (unit: μm), respectively. Also, R0 is the return loss at the flat end face, which can be expressed by Equation 3.

number

[0045] In this embodiment, when the wavelength λ is 1310 nm and the mode field radius ω1 is 4.5 μm, the return loss R0 at the flat end facet is 14.7 dB, and a return loss R of 40 dB or more can be maintained by, for example, making the angle of the annular portion S20 with respect to the tip portion S19 5 degrees or more.

[0046] Figure 10 shows the excess loss T versus the gap G. G In the optical coupling between the fixed-side optical fiber S8 and the rotation-side optical fiber S9, if a gap G exists between the end face of the fixed-side optical fiber S8 and the end face of the rotation-side optical fiber S9, the distribution of the output light from the fixed-side optical fiber S8 spreads and the coupling efficiency with the core of the rotation-side optical fiber S9 decreases, which causes excess loss.

[0047] Gap G (unit: μm) and excess loss T G The relationship (unit: dB) can be expressed by Equation 4.

number

[0048] 10 shows the loss when the mode field radii of the cores of the fixed-side optical fiber S8 and the rotating-side optical fiber S9 are both 4.5 μm. For example, by adjusting the gap G between the end face of the fixed-side optical fiber S8 and the end face of the rotating-side optical fiber S9 to 20 μm or less, the excess loss can be suppressed to 0.1 dB or less.

[0049] Next, a description will be given of the requirements for the actuator S11 in Fig. 2, the fixed ferrule S13 described in Fig. 4, and the rotating ferrule S14 described in Fig. 5. The actuator S11 is a drive mechanism that rotates at any angle step in response to a pulse signal from a control circuit S12 and has a constant static torque for each angle step, and for example, a stepping motor is used.

[0050] In addition, the actuator S11 may use other methods as long as it is a driving mechanism that rotates at any angle step by a pulse signal from the control circuit S12 and has a constant static torque for each angle step. The rotation speed and rotation angle are determined by the period and number of pulses of the pulse signal from the control circuit 12, and the angle step and static torque may be adjusted via a reduction gear. As described above, the rotating ferrule S14 in the optical connecting device is designed to rotate around the central axis Ac, so that the static torque required to hold the rotation angle of the rotating ferrule S14 is provided by the actuator S11. This makes it possible to provide a low-power optical switch that has a self-holding function that does not require power when stationary after switching and can minimize the driving energy when switching the optical path.

[0051] Here, in the stepping motor, if the number of angle steps at which the angular position is maintained when the power supply is stopped is defined as the static angle step number, the static angle step number is a natural number multiple of the number of cores having the same core arrangement radius Rcore of the rotation-side optical fiber S9.

[0052] In addition, the excess loss due to the rotation angle deviation in the optical connection device is R (unit: dB), the rotation angle deviation related to the static angle accuracy of the stepping motor is Φ (unit: degrees), and the core arrangement radius Rcore (unit: μm), the relationship between these can be expressed by Equation 5.

number

[0053] Excess loss T due to rotation angle deviation relative to core placement radius Rcore RAn example of the relationship is shown in Figure 11. Generally, the angle accuracy of a stepping motor is about 3 to 5%, and in Figure 11, the rotation angle deviation Φ is set to 0.05 degrees. The larger the core arrangement radius Rcore is, the larger the excess loss becomes, so strict static angle accuracy is required. For example, if the excess loss is 0.1 dB, when the mode field radii ω1 and ω2 are 4.5 μm (MFD = 9 μm), the core arrangement radius Rcore must be 800 μm or less. Also, if an optical fiber with a larger mode field radius is used, it is possible to reduce the excess loss.

[0054] However, in order to achieve the excess loss due to the rotation angle deviation shown in Fig. 11, the fixed-side ferrule S13 needs to be stationary in the rotation angle direction. Furthermore, if the rotating mechanism S10 shown in Fig. 2 moves horizontally and vertically with respect to the cross section when rotating like the shaft of a motor, for example, the rotating-side ferrule moves horizontally and vertically with respect to the ferrule end face, so a mechanism is needed for the fixed-side ferrule S13 to move horizontally and vertically following the rotating-side ferrule S14.

[0055] 12 is a schematic diagram showing a cross section of the inside of the fixed-side flange holding portion S16 according to an embodiment of the present disclosure. The fixed-side flange S26 has grooves at the top and bottom, and the interference portion S25 has protrusions that engage with the grooves provided at the top and bottom of the fixed-side flange S26. A gap is provided between the interference portion S25 and the upper and lower parts of the fixed-side flange S26, and the fixed-side flange S26 moves up and down (vertically on the ferrule end surface). The interference portion S25 has grooves at the left and right, and the outer frame portion S27 has protrusions that engage with the grooves provided at the left and right of the interference portion S25. A gap is provided between the outer frame portion S27 and the left and right parts of the interference portion S25, and the interference portion S25 moves left and right (horizontally on the ferrule end surface).

[0056] 12, the fixed flange S26 and the interference portion S25 are each provided with a pair of grooves and protrusions on the top and bottom, but the number of grooves and protrusions is not limited to this as long as they can move up and down. Also, the interference portion S25 and the outer frame portion S27 are each provided with a pair of grooves and protrusions on the left and right, but the number of grooves and protrusions is not limited to this as long as they can move left and right.

[0057] Also, the fixed side flange S26 moves up and down and the interference portion S25 moves left and right, but this is not limited as long as the end face of the fixed side ferrule S13 can move up, down, left and right (horizontally and vertically). For example, grooves may be provided on the left and right of the fixed side flange S26 to move left and right, and grooves may be provided on the top and bottom of the interference portion S25 to move up and down, thereby moving the end face of the fixed side ferrule S13 up, down, left and right (horizontally and vertically).

[0058] Also, the fixed-side flange S26 has a circular groove, but may have a shape other than circular as long as it can move up and down. In this way, by limiting the range of movement of the fixed-side flange S26, the interference portion S25, and the outer frame portion S27 with the grooves and protrusions on the top, bottom, left, and right, it is possible to hold the end face of the fixed-side ferrule S13 so that it can move in the horizontal and vertical directions and not rotate around the ferrule axis.

[0059] The present disclosure relates to The end faces of two ferrules, each having a single-core fiber arranged parallel to the central axis Ac and at the same distance from the central axis Ac, are butted together so that the central axes Ac coincide with each other. A flange attached to one of the ferrules is held by a holder so as to be movable in horizontal and vertical directions relative to the end face of the ferrule and not rotate around a central axis Ac; and The spring presses the two ferrule ends together, The other ferrule is rotated about the central axis Ac.

[0060] As a result, the present disclosure makes it possible to switch opposing optical fibers while maintaining good optical properties. By making the ends of the two ferrules convex, butting the tips S19 of the ends of the two ferrules together so that their central axes coincide, and rotating one of the ferrules, 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 properties such as connection loss caused by scratches on the end faces of the optical fibers due to contact. In addition, by making the end faces of the opposing optical fibers non-parallel to each other, it is possible to reduce the amount of light reflection, and therefore it is possible to provide a more economical optical connection device and an optical switch using the same, without requiring a reflective coating.

[0061] Furthermore, in this disclosure, one of the input side and the output side of the optical connection device that performs optical switching is an axially rotatable mechanism, so that it is possible to minimize the energy required by the actuator, i.e., the torque output, and to reduce power consumption. Also, the amount of optical axis deviation in a direction other than the axial rotation of the rotating ferrule S14 is guaranteed by the cylindrical sleeve S15, so that it is possible to reduce loss. In addition, this disclosure does not include a collimator or a special vibration isolation mechanism, and is made up of commonly used optical connection parts such as ferrules and sleeves, so it is small and economical.

[0062] Therefore, the present disclosure makes it possible to provide an optical connection device and an optical switch using the same that can realize stable optical characteristics against external factors such as temperature and vibration with low power consumption and more economically. As a result, the device can be used as an optical switch that switches paths in optical lines using single-mode optical fibers in optical fiber networks, regardless of location, in any facility.

[0063] (Embodiment 2) 13 is a schematic diagram showing a cross section of the inside of the fixed-side flange holding portion S16 according to an embodiment of the present disclosure. By providing springs S30 on the top, bottom, left, and right of the fixed-side flange S28 and fixing them to the inside of the outer frame portion S29, the fixed-side ferrule can move horizontally and vertically on the ferrule end face in accordance with the rotating-side ferrule that moves horizontally and vertically in the same manner due to the horizontal and vertical movement of the shaft of a motor, for example. By providing multiple springs S30 with the same spring constant on the top, bottom, left, and right of the fixed-side flange S28, it is possible to keep the fixed-side flange S28 stationary in the rotation angle direction.

[0064] 13, two springs S30 are provided on each of the top, bottom, left and right of the fixed-side flange S28, but the number is not limited to this as long as it allows the fixed-side ferrule to move horizontally and vertically on the ferrule end face following the rotating-side ferrule and remains stationary in the rotation angle direction. Also, the members attached to the top, bottom, left and right of the fixed-side flange S28 may be elastic, and for example, rubber may be used instead of the springs. [Industrial Applicability]

[0065] The optical connecting device and the optical switch using the same according to the present disclosure can be applied to the optical communications industry. [Explanation of symbols]

[0066] S1: Input optical fiber S2: Optical fiber between optical switches S3: Rear-stage optical switch component S4: Output optical fiber S5: Front-stage optical switch component S6: Rotating side flange S7: Holder S8: Fixed optical fiber S9: Rotation side optical fiber S10: Rotation mechanism S11: Actuator S12: Control circuit S13: Fixed side ferrule S14: Rotating side ferrule S15: Cylindrical sleeve S16: Fixed side flange holding part S17: Spring S18: Flange holding part fixing protrusion S19:Tip S20: Circular ring S21, S23: Ferrule outer diameter S22, S26, S28: Fixed side flange S23: Ferrule outer diameter S24: Sleeve inner diameter S25: Interference part S27, S29: Outer frame S30: Spring

Claims

1. A first ferrule in which the core centers of one or more single-core fibers are arranged on the same circumference from the center in a cross section of the ferrule; a second ferrule in which 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 centers of the single-core fibers in the first ferrule are arranged, the circumference being located from the center in a cross section of the ferrule; a cylindrical sleeve having a hollow portion into which the first ferrule and the second ferrule are inserted so that central axes of the first ferrule and the second ferrule are aligned, and a predetermined gap is provided between the outer diameter of each of the first ferrule and the second ferrule and the inner diameter of the hollow portion so that the first ferrule or the second ferrule can rotate; a spring that applies pressure to a first flange of the first ferrule or a second flange of the second ferrule so as to butt a tip end portion of the first ferrule against a tip end portion of the second ferrule; a holder that holds the first ferrule, the second ferrule, the cylindrical sleeve, the first flange, the second flange, and the spring such that central axes of the first ferrule and the second ferrule are aligned, the first ferrule or the second ferrule is held by the holder so as to be movable in any direction perpendicular to the central axis within the holder and not to rotate around the central axis; the first ferrule and the second ferrule each have a tip portion in the central axis direction, The end of the first ferrule comprises: The tip portion, a ring portion disposed on an outer periphery of the tip portion and exposing an end face of the single-core fiber disposed in the first ferrule; The end of the second ferrule comprises: The tip portion, a ring portion disposed on an outer periphery of the tip portion and exposing an end face of the single-core fiber disposed in the second ferrule; The tip of the first ferrule and the tip of the second ferrule are butted against each other.

1. An optical connection device comprising:

2. The tip of the first ferrule and the tip of the second ferrule are flat surfaces perpendicular to the central axis.

2. The optical connecting device according to claim 1.

3. In each of the tip portion of the first ferrule and the tip portion of the second ferrule, an angle between the flat surface of the tip portion and the annular portion is 5 degrees or more.

3. The optical connecting device according to claim 2.

4. A gap between an end face of a single-core fiber exposed in the annular portion of the first ferrule and an end face of a single-core fiber exposed in the annular portion of the second ferrule, the optical axis of which coincides with that of the single-core fiber, is 20 μm or less.

4. The optical connecting device according to claim 1, wherein the optical connecting device is a first optical fiber.

5. In the holder, the first ferrule or the second ferrule is movable in a direction parallel to the central axis.

2. The optical connecting device according to claim 1.

6. An optical connecting device according to any one of claims 1 to 5, a rotation mechanism for rotating either the first ferrule or the second ferrule of the optical connecting device about the central axis.

1. An optical switch comprising:

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