JP2017191251A - Method of centering local light input/output optical system and local light input/output optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber side input/output device and a probe position centering method which can easily center a probe of a double clad fiber.SOLUTION: An optical fiber side input/output device 301 performs a roughly centering step for moving a position of one end 31 of a probe fiber 11, measuring the light intensity of leakage light without passing through a special single mode fiber, obtaining a first fluctuation curve of the light intensity of the leakage light to a position of the one end of the probe fiber, and moving the one end of the probe fiber to a first position which is a center in the full width at half maximum of the first fluctuation curve; and a finely centering step for moving the position of the one end of the probe fiber near the first position, measuring the light intensity of the leakage light through the special single mode fiber, obtaining a second fluctuation curve of the light intensity to the position of the one end of the probe fiber, and moving the one end of the probe fiber to a second position which becomes a peak of a second fluctuation curve to a centering mechanism.SELECTED DRAWING: Figure 7

Description

  The present disclosure relates to a technique for inputting and outputting light from the side of an optical fiber.

  In the local light input / output optical system, if the light receiving coupling efficiency is low, an expensive high-amplification amplifier must be used to compensate. Therefore, it has been proposed to use a double-clad fiber (dual-mode fiber) that has both a single-mode core and a multi-mode core as a probe fiber instead of the conventional single-mode fiber for the purpose of improving the light receiving coupling efficiency. [For example, see Non-Patent Documents 1, 2, and 3. ]. This is because the light receiving coupling efficiency increases as the core diameter of the fiber used for the probe increases.

  In the present specification, the double clad fiber may be abbreviated as “DCF” and the single mode fiber as “SMF”. Further, “single mode fiber” means an optical fiber that propagates only in the fundamental mode at the wavelength of propagating light, and “multimode fiber” means an optical fiber that can propagate in a plurality of modes at the wavelength of propagating light.

  FIG. 1 is a diagram illustrating the structure of a double clad fiber. It consists of a Ge-doped single mode core, an undoped multimode core, and an F-doped cladding. When a single mode fiber is connected, it operates as a single mode fiber, and when a multimode fiber is connected, it operates as a multimode fiber.

  FIG. 2 is a diagram for explaining a state of local light input / output by a double clad fiber. The double clad fiber 11 receives the light (leakage light) output from the bent portion of the main optical fiber 1 with the multimode core (FIG. 2A). For this reason, if a double clad fiber is used, the received light intensity can be increased as compared with the light received by a single mode fiber, so that an inexpensive ordinary amplifier can be used. On the other hand, the double clad fiber 11 allows light to enter the bent portion of the main optical fiber 1 via the single mode core (FIG. 2B). For this reason, if a double clad fiber is used, the beam diameter can be reduced compared to the incidence of a multimode fiber, and the incident coupling efficiency with the main optical fiber 1 can be increased.

  FIG. 3 is a diagram for explaining an optical fiber side input / output device 300 using a double clad fiber. The optical fiber side input / output device 300 includes a local light input / output unit 32 having a probe fiber 31 for local light input / output and a relay amplifier 33. The WDM coupler 34 separates the incident wavelength and the received light wavelength according to the difference in the wavelengths propagating through the single mode core and the multimode core. Incident light is connected from a duplex SFP (small form-factor pluggable) optical transceiver 35 to a probe fiber 31 for local optical input / output via a single mode core of SMF 37, WDM coupler 34, and DCF 11 for local optical input / output. Light received by the probe fiber 31 reaches the duplex SFP optical transceiver 35 via the multimode core of the DCF 11, the WDM coupler 34, and the multimode core of the DCF 38, and is transmitted and received by the duplex SFP optical transceiver 35. After the OE / EO conversion, the station side communicates with the bi-directional SFP optical transceiver 36.

  Tape fibers are widely used as aerial and underground cables in domestic access facilities. Consider applying a local light input / output optical system to a tape fiber. FIG. 4 is a diagram illustrating a typical tape fiber. The tape fiber is composed of four or eight single mode fibers covered with an ultraviolet curable resin having a diameter of 0.25 mm, and is further formed into a tape shape with a resin coating.

  FIG. 5 is a diagram for explaining the state of light leaking from the tape fiber. 5A is a perspective view, and FIG. 5B is a side view. Here, since the thickness of the resin varies in units of several tens of μm, the core interval of each optical fiber varies by several tens of μm and is indefinite. On the other hand, since the core diameter of the optical fiber is about 9 μm, the alignment of the optical axis to the optimum position between the optical fiber cores requires accuracy of several μm. Since the core position of the optical fiber tape varies by about several tens of μm, the side light input / output optical system for the tape fiber needs to align the optical axis to the optimum position each time the target tape fiber is replaced. . In this optical axis alignment, the received light intensity of light emitted from the bent main optical fiber is used as an index. When a probe using a single mode fiber is used, it is possible to fine-tune the optimum position of the probe with an accuracy of several μm by searching for a place where the maximum position is obtained using the received light intensity as an index.

Kiyokura et al., “Study on improvement of light reception efficiency of local optical input / output technology by using dual mode fiber probe”, 2015 IEICE Communication Society b-13-014 Tanabe et al., “SM / MM dual-mode optical fiber”, OCS 2007-37 (2007-8) Internet “Solab double clad fiber DCF13”, https: // www. thorlabs. co. jp / thorcat / TTN / DCF13-SpecSheet. pdf (searched April 1, 2016) Hamada et al., “Study of optical line switching device using side input / output technology”, OFT 2013-50 (2014-1) Internet “Optical Switch”, http: // www. difiberoptics. com / products / scd0227 / 0227a. pdf (searched April 1, 2016)

  FIG. 6 shows the result (position tolerance curve) of the received light intensity with respect to the tip position of the probe light for local light input / output. The local optical input / output optical system using a double-clad fiber (dual-mode fiber) as a probe has a position tolerance curve that is wider than the conventional single-mode fiber. The intensity change in the vicinity is smooth.

  When alignment is performed via a double-clad fiber using the light emitted from the bent portion of the main optical fiber as an index, the position tolerance curve is wide, so the received light intensity is easily increased by coarse alignment, but the intensity change near the peak Therefore, it is difficult to make fine adjustment of several μm level necessary for incidence. If the probe cannot be adjusted to a position suitable for incidence, even if the light receiving coupling efficiency is sufficient, the incident coupling efficiency may be insufficient, transmission may not be performed only by reception, and bi-directional communication may not be established. As described above, an optical fiber side input / output device using a double clad fiber as a probe has a problem that accurate probe alignment is difficult.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical fiber side input / output device and a probe position alignment method that can easily align a probe of a double clad fiber in order to solve the above-described problems.

  The optical fiber side input / output device according to the present invention includes a dedicated single mode fiber used for alignment.

Specifically, an optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light to / from a main optical fiber formed with a bent portion. And
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
A dedicated single mode fiber that can be connected to the other end of the probe fiber and propagates the leaked light that has been propagated by the single mode core of the probe fiber;
A light receiving device that receives the leaked light received by the probe fiber directly from the probe fiber or through the dedicated single mode fiber, and measures the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light measured by the light receiving device;
Is provided.

In particular, the control circuit comprises:
The position of the one end of the probe fiber is moved with respect to the alignment mechanism, the light intensity of the leaked light not passing through the dedicated single mode fiber is measured, and the leaked light with respect to the position of the one end of the probe fiber A first variation curve of the light intensity of
Moving the one end of the probe fiber to a first position which is the center of the full width at half maximum of the first fluctuation curve with respect to the alignment mechanism;
The position of the one end of the probe fiber is moved in the vicinity of the first position with respect to the alignment mechanism, the light intensity of the leaked light through the dedicated single mode fiber is measured, and the probe fiber Obtaining a second fluctuation curve of the light intensity of the leaked light with respect to the position of one end;
The one end of the probe fiber is moved to a second position where the peak of the second fluctuation curve is relative to the alignment mechanism.

That is, the probe position alignment method according to the present invention is a probe position alignment method of the optical fiber side input / output device,
A first fluctuation of the light intensity of the leaked light with respect to the position of the one end of the probe fiber is measured by moving the position of the one end of the probe fiber and measuring the light intensity of the leaked light not through the dedicated single mode fiber. A rough alignment step of obtaining a curve and moving the one end of the probe fiber to a first position which is the center of the full width at half maximum of the first fluctuation curve;
The position of the one end of the probe fiber is moved in the vicinity of the first position, the light intensity of the leaked light through the dedicated single mode fiber is measured, and the leaked light with respect to the position of the one end of the probe fiber A fine alignment step of obtaining a second variation curve of the light intensity and moving the one end of the probe fiber to a second position that is a peak of the second variation curve with respect to the alignment mechanism;
It is characterized by performing.

  When a single-mode fiber is connected to the double-clad fiber, the propagation light of the multimode core is removed, and only the single-mode core propagation light is obtained. During coarse alignment, a double-clad fiber is connected to the light receiving device, and alignment is performed with strong light that has propagated through the multimode core. In the rough centering, since the peak of the position tolerance curve is flat, the left and right shoulders of the peak where the light intensity decreases are detected, and the center position is set as the center position of the subsequent fine centering.

  After that, a dedicated single mode fiber is inserted and connected between the double clad fiber and the light receiving device, and fine alignment is performed to determine and hold the optimum position. After that, the inserted single mode fiber is removed, the double clad fiber is directly connected to the light receiving device, and bidirectional communication is started.

  Accordingly, the present invention can provide an optical fiber side input / output device and a probe position alignment method that facilitate alignment of a double-clad fiber probe.

  The control circuit may further move the one end of the probe fiber to a third position that is a predetermined length away from the second position with respect to the alignment mechanism.

  When the incident wavelength and the light receiving wavelength are different, the optimum position at the incident wavelength may be different from the optimum position at the light receiving wavelength. Therefore, in the above alignment, the relative positional relationship between the optimal position at the incident wavelength and the optimal position at the light receiving wavelength is acquired in advance, and after fine alignment with the dedicated single mode fiber, the probe is moved by the relative position.

  Incident coupling efficiency can be maximized by shifting the probe to the optimal incidence position. On the other hand, the probe is moved away from the optimum light receiving position. However, since light reception is performed by a multimode core having a wide position tolerance, a value close to the optimum value can be obtained for the light receiving coupling efficiency. This optical fiber side input / output device can maintain high coupling efficiency in both transmission and reception even when the incident wavelength and the light receiving wavelength are different.

  The optical fiber side input / output device according to the present invention may have the following configuration.

An optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a dedicated double-clad fiber or a dedicated single-mode fiber;
A light-receiving device for a double-clad fiber that receives the leaked light propagating through the dedicated double-clad fiber connected to the optical switch and measures the light intensity of the leaked light;
A light receiving device for a single mode fiber that receives the leakage light propagating through the dedicated single mode fiber connected to the optical switch and measures the light intensity of the leakage light; and
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light measured by the light receiving device for double clad fiber or the light receiving device for single mode fiber;
Is provided.

An optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
One end can be connected to the other end of the probe fiber, and a dedicated single mode fiber that propagates the leaked light propagated by the single mode core of the probe fiber;
A connector capable of connecting the other end of the probe fiber or the other end of the dedicated single mode fiber;
A duplex optical transceiver that receives the leakage light coupled to the connector with a photodiode and outputs the light intensity of the leakage light; and
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit for causing the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver;
Is provided.

An optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a double-clad fiber relay path or a dedicated single-mode fiber;
A duplex optical transceiver that receives the leaked light propagating through the relay path of the double-clad fiber or the dedicated single-mode fiber with a photodiode and outputs the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit for causing the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver;
Is provided.

An optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a double-clad fiber relay path or a dedicated single-mode fiber;
A duplex optical transceiver that receives the leakage light propagated through the relay path of the double clad fiber with a photodiode and outputs the light intensity of the leakage light;
A light receiving device that receives the leaked light propagated through the dedicated single mode fiber and measures the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver or the light intensity of the leaked light measured by the light receiving device;
Is provided.

  INDUSTRIAL APPLICABILITY The present invention can provide an optical fiber side input / output device and a probe position alignment method that facilitate alignment of a double-clad fiber probe.

It is a figure explaining the structure of a double clad fiber. It is a figure explaining the mode of local light input / output by a double clad fiber. It is a figure explaining the optical fiber side input / output apparatus relevant to this invention. It is a figure explaining a typical tape fiber. It is a figure explaining the mode of the light which leaks from a tape fiber. (A) is a perspective view, (B) is a side view. It is the result (position tolerance curve) which measured the received light intensity with respect to the tip position of a probe fiber. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Connect DCF to PD, receive light via DCF, hold after coarse alignment and peak center estimated position determination. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Dedicated SMF is inserted, fine alignment is performed via SMF, and the probe optimum position is determined and held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Holds the optimal probe position, removes the dedicated SMF, and switches the DCF from the PD to the WDM coupler. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Bidirectional communication is started via the WDM coupler and SFP while keeping the optimum probe position. It is a figure explaining the position tolerance curve of a double clad fiber. It is a figure explaining that the optimal position of a probe fiber changes with the difference in wavelength. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. The SW is connected to the DCF PD, and the light is received via the DCF, and is held after the coarse alignment and the peak center estimated position are determined. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Connect SW to SMF PD, receive light via SMF, and perform rough alignment and hold after determining peak center estimated position. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Bidirectional communication is started via the WDM coupler and SFP while keeping the optimum probe position. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. The DCF is connected to the duplexSFP via the WDM coupler, received through the DCF, and is held after coarse alignment and peak center estimation position determination. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Dedicated SMF is inserted, fine alignment is performed via SMF, and the probe optimum position is determined and held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. The dedicated SMF is removed while maintaining the optimum probe position. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. Connect the DCF to the WDM coupler. Bidirectional communication starts via the WDM coupler and duplexSFP. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. SW is set so as to be incident on the duplex SFP via the DCF, received through the DCF, and after the coarse alignment and the peak center estimated position determination, is held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. SW is set via SMF, fine alignment is performed via SMF, and the probe optimum position is determined and held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. The SW is set to enter the SFP via the DCF, and bidirectional communication is started via the duplex SFP. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. SW is set so as to be incident on the duplex SFP via the DCF, received through the DCF, and after the coarse alignment and the peak center estimated position determination, is held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. SW is set via SMF, fine alignment is performed via SMF, and the probe optimum position is determined and held. It is a figure explaining the optical fiber side input / output apparatus which concerns on this invention. The SW is set to enter the SFP via the DCF, and bidirectional communication is started via the duplex SFP.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are embodiments of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
7 to 10 are diagrams for explaining the optical fiber side input / output device 301 of this embodiment. The optical fiber side input / output device 301 is an optical fiber side input / output device that inputs / outputs light to / from the main optical fiber 1 formed with a bent portion through the bent portion,
A double-clad fiber 11 having a single-mode core and a multi-mode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single-mode core in the cross section of the one end, and leaks from the bent portion A probe fiber 31 that receives leaked light with a single-mode core and a multi-mode core at the cross section of the one end;
A dedicated single mode fiber 19 that can be connected to the other end of the probe fiber 31 and propagates the leaked light propagated by the single mode core of the probe fiber 31;
A light receiving device 15 that receives the leakage light received by the probe fiber 31 directly from the probe fiber 31 or via the dedicated single mode fiber 19 and measures the light intensity of the leakage light;
An alignment mechanism 12 for adjusting the position of the one end of the probe fiber 31;
A control circuit 17 that causes the alignment mechanism 12 to adjust the position of the one end of the probe fiber 31 based on the light intensity of the leaked light measured by the light receiving device 15;
Is provided.
The optical fiber side input / output device 301 further includes a repeater amplifier 33 having a WDM coupler 34, a duplex SFP optical transceiver 35, a bi-directional SFP optical transceiver 36, an SMF 37, and a DCF 38. The probe light 31 and the alignment mechanism 12 are provided in the local light input / output unit 32. The light receiving device 15 and the control circuit 17 may be in the relay amplifier 33.

  In the example shown in FIG. 3, the probe fiber 31 is fixed. However, in this embodiment, the probe fiber 31 is mounted on the alignment mechanism 12, and the position is controlled by the control circuit 17. Further, a high sensitivity photodiode (PD) is connected to the control circuit 17 as the light receiving device 15. This PD is used for position search and needs only to have high sensitivity and not for communication. Therefore, a low-speed and inexpensive one can be used.

  The control circuit 17 uses the light intensity received by the light receiving device 15 as an index to give an instruction to the alignment mechanism 12 so that the tip of the probe fiber 31 is at the optimum position, and performs rough alignment and fine alignment. The procedure is shown below.

The control circuit 17
The position of the one end of the probe fiber 31 is moved with respect to the aligning mechanism 12, the light intensity of the leaked light not passing through the dedicated single mode fiber 19 is measured, and the leaked light with respect to the position of the one end of the probe fiber 31 is measured. A first variation curve of the light intensity of
Moving the one end of the probe fiber 31 to the first position which is the center of the full width at half maximum of the first fluctuation curve with respect to the aligning mechanism 12;
The position of the one end of the probe fiber 31 is moved in the vicinity of the first position with respect to the aligning mechanism 12, and the light intensity of the leaked light through the dedicated single mode fiber 19 is measured. Obtaining a second fluctuation curve of the light intensity of the leaked light with respect to the position of one end;
The one end of the probe fiber 31 is moved to the second position at which the second fluctuation curve reaches the peak with respect to the aligning mechanism 12.

(Procedure 1: FIG. 7) The DCF 11 connected to the probe fiber 31 is connected to the light receiving device 15. Coarse alignment is performed by the control circuit 17 and the alignment mechanism 12 using the light intensity (first fluctuation curve) received through the DCF 11 as an index. Specifically, the control circuit 17 estimates the peak center from the first fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 2: FIG. 8) A dedicated SMF 19 is inserted between the DCF 11 and the light receiving device 15, and the control circuit 17 and the alignment mechanism 12 perform fine alignment using the light intensity (second fluctuation curve) received through the dedicated SMF 19 as an index. I do. Specifically, the control circuit 17 detects the peak center from the second fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position. The dedicated SMF 19 may be installed in advance on the housing surface of the relay amplifier 33. The relationship between the first fluctuation curve and the second fluctuation curve will be described later.

(Procedure 3: FIG. 9) While maintaining the optimum position of the probe fiber 31 found in Procedure 2, the dedicated SMF 19 that has been interrupted is removed, and the DCF 11 is switched to the WDM coupler 34.

(Procedure 4: FIG. 10) Bidirectional communication is started while the optimum position of the probe fiber 31 is maintained. Specifically, leakage light from the main optical fiber 1 passes through the probe fiber 31 and the single mode core and the multimode core of the DCF 11, is input to the DCF 38 by the WDM coupler 34, and is O / E converted by the duplex SFP optical transceiver 35. Is done. Then, the O / E converted electrical signal is E / O converted by the bi-directional SFP optical transceiver 36 and transmitted to the station side. On the other hand, the signal from the station side is O / E converted by the bi-directional SFP optical transceiver 36 and E / O converted by the duplex SFP optical transceiver 35. This E / O converted optical signal passes through the SMF 37 and is coupled to the DCF 11 by the WDM coupler 34. This optical signal is emitted from the single mode core of the probe fiber 31 and input to the main optical fiber 1.

  As described above, this probe position alignment method performs rough alignment using the first fluctuation curve intensity of the light intensity acquired using the light via the multimode core of the DCF 11 as an index, and then via the single mode core via the dedicated SMF 19. The second fluctuation curve intensity of the light intensity acquired using the light of the above is finely adjusted as an index. For this reason, both the incident on the main optical fiber 1 and the leaked light from the main optical fiber 1 can be bidirectionally communicated with enhanced coupling efficiency.

(Embodiment 2)
In the present embodiment, details of the probe positioning method of the optical fiber side input / output device 301 described in the first embodiment will be described. FIG. 11 is a diagram illustrating the first variation curve and the second variation curve.

  The light intensity of leakage light having a wavelength of 1310 nm emitted from the bent portion of the main optical fiber 1 is adjusted as an index. Since the leakage light is received by the multimode core (including the single mode core) of the probe fiber 31, the first fluctuation curve that is the relationship between the position of the tip of the probe fiber 31 and the light intensity of the leakage light has a wide shape. Yes (solid line), full width at half maximum is about 71 μm. Although the received light intensity is large, the optimum position for receiving light when the full width at half maximum is wide and leak light is received by a single mode fiber is unknown. Therefore, the center position of the coordinate that is the half value of the maximum intensity at the peak of the first curve is set as a temporary optimal light receiving position (first position). In this graph, it is around 889.6 μm.

  Subsequently, the tip of the probe fiber 31 is moved to a temporary optimal light receiving position. Next, the dedicated SMF 19 is divided between the DCF 11 and the light receiving device 15 to obtain a second fluctuation curve that is a relationship between the position of the tip of the probe fiber 31 and the light intensity of the leaked light in the vicinity of the temporary light receiving optimum position. . The second fluctuation curve is shown by a broken line. The optimum light receiving position (true optimum light receiving position: second position) when the dedicated SMF 19 is inserted and light is received by the single mode core of the probe fiber 31 is about 883 μm.

  The difference between the temporary optimum light receiving position and the true optimum light receiving position is only 6.6 μm, and they are close to each other. In this way, the multimode core including the single mode core of the probe fiber 31 performs rough alignment for receiving the leaked light to set the temporary optimum light receiving position, and then the single mode core near the temporary optimum light receiving position. By performing fine alignment for receiving leaked light, alignment can be performed accurately in a short time.

(Embodiment 3)
In the present embodiment, another method for aligning the probe position of the optical fiber side input / output device 301 described in the second embodiment will be described. In the present embodiment, the control circuit 17 further moves the one end of the probe fiber 31 to a third position that is a predetermined length away from the second position with respect to the alignment mechanism 12.

  In the second embodiment, the position is optimized using light emitted from the bent portion as an index. When the wavelength of the incident light is different from the wavelength of the received light, the refractive index of the optical material is different, so the maximum position of the light receiving coupling efficiency and the maximum position of the incident coupling efficiency are generally different, but the relative positional relationship is is there. This relative positional relationship can be measured at the time of manufacturing the apparatus, or can be obtained by simulation. FIG. 12 is a simulation of the second fluctuation curve when the leaked light with a wavelength of 1310 nm and the leaked light with a wavelength of 1550 nm are received by the single mode core of the probe fiber 31. The difference between the second fluctuation curve having a wavelength of 1310 nm and the second fluctuation curve having a wavelength of 1550 nm is the relative positional relationship.

  Here, it is assumed that light having a wavelength of 1310 nm propagating through the main optical fiber 1 is received and light having a wavelength of 1550 nm is incident on the main optical fiber 1. From FIG. 12, even if the probe fiber 31 is finely aligned by the probe position alignment method as in the second embodiment using the leaked light having the wavelength of 1310 nm, the optimum position of the probe fiber 31 that makes the light having the wavelength of 1550 nm incident on the main optical fiber 1. Is expected to be 8 μm off.

  Therefore, after the probe fiber 31 is aligned to the optimum position by the probe position alignment method as in the second embodiment using the received wavelength, the incident coupling efficiency investigated in advance at the desired wavelength is optimized. Incident coupling efficiency can be maximized by shifting the probe fiber 31 to the position (third position). By moving the probe fiber 31 to a position where the incident coupling efficiency is maximized, the probe fiber 31 is moved away from the optimum position of the light receiving coupling efficiency by the single mode core, but light reception is performed by the multimode core having a wide position tolerance. A value close to the optimum value can be obtained for the light receiving coupling efficiency.

(Embodiment 4)
FIG. 13 to FIG. 15 are diagrams for explaining the optical fiber side input / output device 302 of the present embodiment. The optical fiber side input / output device 302 is an optical fiber side input / output device that inputs / outputs light to / from the main optical fiber 1 formed with a bent portion through the bent portion.
A double-clad fiber 11 having a single-mode core and a multi-mode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single-mode core in the cross section of the one end, and leaks from the bent portion A probe fiber 31 that receives leaked light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch 21 for coupling the leaked light propagated by the probe fiber 31 to the dedicated double-clad fiber 20 or the dedicated single-mode fiber 19;
A light receiving device 15A for a double clad fiber that receives the leaked light propagating through a dedicated double clad fiber 20 connected to the optical switch 21 and measures the light intensity of the leaked light;
A single-mode fiber light receiving device 15B that receives the leakage light propagating through the dedicated single-mode fiber 19 connected to the optical switch 21 and measures the light intensity of the leakage light;
An alignment mechanism 12 for adjusting the position of the one end of the probe fiber 31;
A control circuit 17 that causes the alignment mechanism 12 to adjust the position of the one end of the probe fiber 31 based on the light intensity of the leakage light measured by the light receiving device 15A for double clad fiber or the light receiving device 15B for single mode fiber;
Is provided.
The optical fiber side input / output device 302 further includes a relay amplifier 33 having a WDM coupler 34, a duplex SFP optical transceiver 35, a bi-directional SFP optical transceiver 36, an SMF 37, and a DCF 38. The probe light 31 and the alignment mechanism 12 are provided in the local light input / output unit 32. The optical switch 21, the light receiving device (15 </ b> A, 15 </ b> B), and the control circuit 17 may be in the relay amplifier 33.

  The optical fiber side input / output device 301 of the first embodiment performs probe position alignment by inserting the dedicated SMF 19. The optical fiber side input / output device 302 can automate the interruption of the dedicated SMF 19 by introducing the optical switch 21 (see, for example, Non-Patent Document 5). The DCF 11 from the probe fiber 31 is connected to the optical switch 21. The optical switch 21 is connected to the WDM coupler 34, the DCF light receiving device 15A, and the SMF light receiving device 15B, and can be switched to each other. The light receiving device 15A for DCF and the light receiving device 15B for SMF are high-sensitivity PDs similar to the light receiving device 15 described in the first embodiment.

The procedure is shown below. The operation of the optical switch 21 may be performed by an instruction from the control circuit 17.
(Procedure 1: FIG. 13) The light from the DCF 11 is connected to the dedicated DCF 20 by operating the optical switch 21 and adjusted with the control circuit 17 using the light intensity (first fluctuation curve) received by the DCF light receiving device 15A as an index. The center mechanism 12 performs rough alignment. Specifically, the control circuit 17 estimates the peak center from the first fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 2: FIG. 14) The light from the DCF 11 is connected to the dedicated SMF 19 by operating the optical switch 21 and adjusted with the control circuit 17 using the light intensity (second fluctuation curve) received by the SMF light receiving device 15B as an index. The center mechanism 12 performs fine alignment. Specifically, the control circuit 17 detects the peak center from the second fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 3: FIG. 15) While maintaining the optimum position of the probe fiber 31, the optical switch 21 is operated to connect the light from the DCF 11 to the WDM coupler 34 to start bidirectional communication. The signal flow of bidirectional communication is the same as that described in the first embodiment.

  As described above, by adjusting the position of the probe fiber 31 by this probe positioning method, two-way communication is possible with the coupling efficiency of both the incident light on the main optical fiber 1 and the leaked light from the main optical fiber 1 enhanced. become.

(Embodiment 5)
16 to 19 are diagrams for explaining the optical fiber side input / output device 303 of this embodiment. The optical fiber side input / output device 303 is an optical fiber side input / output device that inputs and outputs light through the bent portion with respect to the main optical fiber 1 in which the bent portion is formed.
A double-clad fiber 11 having a single-mode core and a multi-mode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single-mode core in the cross section of the one end, and leaks from the bent portion A probe fiber 31 that receives leaked light with a single-mode core and a multi-mode core at the cross section of the one end;
One end can be connected to the other end of the probe fiber 31, and the dedicated single mode fiber 19 that propagates the leaked light propagated by the single mode core of the probe fiber 31;
A connector 22 to which the other end of the probe fiber 31 or the other end of the dedicated single mode fiber 19 can be connected;
A duplex optical transceiver 35 that receives the leakage light coupled to the connector 22 with a photodiode and outputs the light intensity of the leakage light;
An alignment mechanism 12 for adjusting the position of the one end of the probe fiber 31;
a control circuit 17 that causes the alignment mechanism 12 to adjust the position of the one end of the probe fiber 31 based on the light intensity of the leaked light output from the duplex optical transceiver 35;
Is provided.
The optical fiber side input / output device 303 further includes a relay amplifier 33 having a WDM coupler 34, a bi-directional SFP optical transceiver 36, an SMF 37, and a DCF 38. The probe light 31 and the alignment mechanism 12 are provided in the local light input / output unit 32. The control circuit 17 may be in the relay amplifier 33.

  In the optical fiber side input / output device 301 of the first embodiment and the optical fiber side input / output device 302 of the fourth embodiment, a light receiving device is prepared. A light reception intensity output terminal may be added to the duplexSFP optical transceiver 35 to externally output the light reception intensity of the communication light reception APD and use it for probe position alignment. In the optical fiber side input / output device 303, the duplex SFP optical transceiver 35 includes a light reception intensity output terminal, so that the photodiode in the duplex SFP optical transceiver 35 is substituted for the light receiving device.

The optical fiber side input / output device 303 interrupts and connects the dedicated SFP 19 between the DCF 11 and the WDM coupler 34 only during fine alignment as in the optical fiber side input / output device 301 of the first embodiment. The procedure is shown below.
(Procedure 1: FIG. 16) The DCF 11 is connected to the connector 22, and the light from the DCF 11 is connected to the duplexSFP optical transceiver 35 through the path of the WDM coupler 34 and the DCF 38 (all path DCF). The control circuit 17 and the aligning mechanism 12 perform rough alignment using the light intensity (first fluctuation curve) received by the photodiode of the duplexSFP optical transceiver 35 as an index. Specifically, the control circuit 17 estimates the peak center from the first fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 2: FIG. 17) The dedicated SMF 19 is inserted between the DCF 11 and the connector 22 and connected to the duplex SFP optical transceiver 35 through the path of the dedicated SMF 19, the WDM coupler 34, and the DCF 38. The control circuit 17 and the alignment mechanism 12 perform fine alignment using the light intensity (second fluctuation curve) received by the photodiode of the duplexSFP optical transceiver 35 as an index. Specifically, the control circuit 17 detects the peak center from the second fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position. The dedicated SMF 19 may be installed in advance on the housing surface of the relay amplifier 33.

(Procedure 3: FIG. 18) The interrupted dedicated SMF 19 is removed while maintaining the optimum position of the probe fiber 31 found in Procedure 2.

(Procedure 4: FIG. 19) The DCF 11 is connected to the connector 22 and switched. Bidirectional communication is started by connecting the light from the DCF 11 to the WDM coupler 34. The signal flow of bidirectional communication is the same as that described in the first embodiment.

  As described above, by adjusting the position of the probe fiber 31 by this probe positioning method, two-way communication is possible with the coupling efficiency of both the incident light on the main optical fiber 1 and the leaked light from the main optical fiber 1 enhanced. become.

(Embodiment 6)
20 to 22 are diagrams illustrating the optical fiber side input / output device 304 of the present embodiment. The optical fiber side input / output device 304 is an optical fiber side input / output device that inputs / outputs light to / from the main optical fiber 1 formed with a bent portion through the bent portion,
A double-clad fiber 11 having a single-mode core and a multi-mode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single-mode core in the cross section of the one end, and leaks from the bent portion A probe fiber 31 that receives leaked light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch 23 for coupling the leaked light propagated by the probe fiber 31 to the relay path 25 of the double clad fiber or the dedicated single mode fiber 19;
A duplex optical transceiver 35 that receives the leakage light propagated through the double-clad fiber relay path 25 or the dedicated single-mode fiber 19 with a photodiode and outputs the light intensity of the leakage light;
An alignment mechanism 12 for adjusting the position of the one end of the probe fiber 31;
a control circuit 17 that causes the alignment mechanism 12 to adjust the position of the one end of the probe fiber 31 based on the light intensity of the leaked light output from the duplex optical transceiver 35;
Is provided.
The optical fiber side input / output device 304 further includes a repeater amplifier 33 having a WDM coupler 34, an optical switch 24, a bi-directional SFP optical transceiver 36, an SMF 37, and a DCF 38. The optical switch 24 couples either the light from the dedicated SMF 19 or the light from the WDM coupler 34 to the DCF 38. The probe light 31 and the alignment mechanism 12 are provided in the local light input / output unit 32. The optical switch 23 and the control circuit 17 may be in the relay amplifier 33.

  The optical fiber side input / output device 304 uses a duplexSFP optical transceiver 35 having a received light intensity output terminal similarly to the optical fiber side input / output device 303 of the fifth embodiment, and the optical switch 23 is used only when the probe fiber 31 is finely aligned. In this configuration, the light passing through the dedicated SMF 19 is coupled to the duplexSFP optical transceiver 35. More specifically, two optical switches are provided before and after the WDM coupler 34 (reference numerals 23 and 24), and leakage light is transmitted via the dedicated SMF 19 instead of the WDM coupler 34 at the time of fine alignment.

The procedure is shown below. The operation of the optical switches 23 and 24 may be performed by an instruction from the control circuit 17.
(Procedure 1: FIG. 20) The optical switch 23 is operated, and the light from the DCF 11 is incident on the duplex SFP optical transceiver 35 through the path of the relay path 25, the WDM coupler 34, the optical switch 24, and the DCF 38 (all paths DCF). The control circuit 17 and the aligning mechanism 12 perform rough alignment using the light intensity (first fluctuation curve) received by the photodiode of the duplexSFP optical transceiver 35 as an index. Specifically, the control circuit 17 estimates the peak center from the first fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 2: FIG. 21) The optical switch 23 is operated to connect the light from the DCF 11 to the dedicated SMF 19, and to the duplex SFP optical transceiver 35 through the path of the dedicated SMF 19, the optical switch 24 and the DCF 38. The control circuit 17 and the alignment mechanism 12 perform fine alignment using the light intensity (second fluctuation curve) received by the photodiode of the duplexSFP optical transceiver 35 as an index. Specifically, the control circuit 17 detects the peak center from the second fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 3: FIG. 22) While maintaining the optimum position of the probe fiber 31, the optical switch 23 is operated and the light from the DCF 11 is duplexed through the relay path 25, the WDM coupler 34, the optical switch 24, and the DCF 38. 35 to enter the two-way communication. The signal flow of bidirectional communication is the same as that described in the first embodiment.

  As described above, by adjusting the position of the probe fiber 31 by this probe positioning method, two-way communication is possible with the coupling efficiency of both the incident light on the main optical fiber 1 and the leaked light from the main optical fiber 1 enhanced. become.

(Embodiment 7)
23 to 25 are diagrams for explaining the optical fiber side input / output device 305 of the present embodiment. The optical fiber side input / output device 305 is an optical fiber side input / output device that inputs / outputs light to / from the main optical fiber 1 formed with a bent portion through the bent portion.
A double-clad fiber 11 having a single-mode core and a multi-mode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single-mode core in the cross section of the one end, and leaks from the bent portion A probe fiber 31 that receives leaked light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch 26 for coupling the leaked light propagated by the probe fiber 31 to the relay path 25 of the double clad fiber or the dedicated single mode fiber 19;
A duplex optical transceiver 35 that receives the leakage light propagated through the double-clad fiber relay path 25 with a photodiode and outputs the light intensity of the leakage light;
A light receiving device 15 that receives the leakage light propagated through the dedicated single mode fiber 19 and measures the light intensity of the leakage light;
An alignment mechanism 12 for adjusting the position of the one end of the probe fiber 31;
a control circuit 17 that causes the alignment mechanism 12 to adjust the position of the one end of the probe fiber 31 based on the light intensity of the leaked light output from the duplex optical transceiver 35 or the light intensity of the leaked light measured by the light receiving device 15;
Is provided.
The optical fiber side input / output device 305 further includes a relay amplifier 33 having a WDM coupler 34, a bi-directional SFP optical transceiver 36, an SMF 37, and a DCF 38. The probe light 31 and the alignment mechanism 12 are provided in the local light input / output unit 32. The optical switch 26, the relay path 25, the light receiving device 15, and the control circuit 17 may be in the relay amplifier 33.

  In the optical fiber side input / output device 304 of the sixth embodiment, coarse alignment and fine alignment are performed using the signal from the received light intensity output terminal of the duplexSFP optical transceiver 35 as an index. Since the light passing through the dedicated SMF 19 at the time of fine alignment is weak, the optical fiber side input / output device 305 uses the high-sensitivity light receiving device 15 (for example, a high-sensitivity large-diameter photodiode) only at the time of fine alignment.

The procedure is shown below. The operation of the optical switch 26 may be performed by an instruction from the control circuit 17.
(Procedure 1: FIG. 23) The optical switch 26 is operated to connect the light from the DCF 11 to the duplex SFP optical transceiver 35 through the relay path 25, the WDM coupler, and the DCF 38 (all paths DCF). The control circuit 17 and the aligning mechanism 12 perform rough alignment using the light intensity (first fluctuation curve) received by the photodiode of the duplexSFP optical transceiver 35 as an index. Specifically, the control circuit 17 estimates the peak center from the first fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 2: FIG. 24) The optical switch 26 is operated to connect the light from the DCF 11 to the dedicated SMF 19 and the light intensity (second fluctuation curve) received by the light receiving device 15 is used as an index to control the circuit 17 and the alignment mechanism. At twelve, make a fine alignment. Specifically, the control circuit 17 detects the peak center from the second fluctuation curve, moves the probe fiber 31 to the position, and holds the probe fiber 31 at the position.

(Procedure 3: FIG. 25) While maintaining the optimum position of the probe fiber 31, the optical switch 21 is operated to connect the light from the DCF 11 to the WDM coupler 34 to start bidirectional communication. The signal flow of bidirectional communication is the same as that described in the first embodiment.

  As described above, by adjusting the position of the probe fiber 31 by this probe positioning method, two-way communication is possible with the coupling efficiency of both the incident light on the main optical fiber 1 and the leaked light from the main optical fiber 1 enhanced. become.

(Other embodiments)
In addition, although Embodiment 1-7 demonstrated the case where the main optical fiber was 1 core for the sake of simplicity, when it is a tape fiber with two or more main optical fibers (FIG. 4), it is light for the number of core wires. Use fiber I / O devices.

  Further, the bent portion of the main optical fiber can be formed with a jig as described in Non-Patent Document 4, for example.

1: Main optical fiber 11: DCF
12: Alignment mechanism 14: GRIN lens 15: Light receiving device 15A: Light receiving device for DCF 15B: Light receiving device for SMF 17: Control circuit 19: Dedicated SMF
20: Dedicated DCF
21, 23, 24, 26: optical switch 22: connector 25: relay path 31: probe fiber 32: local optical input / output unit 33: relay amplifier 34: WDM coupler 35: duplex SFP optical transceiver 36: bi-directional SFP optical transceiver 37: SMF (single mode fiber)
38: DCF (double clad fiber)
300-305: Optical fiber side input / output device

Claims (8)

An optical fiber side input / output device that inputs and outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
A dedicated single mode fiber that can be connected to the other end of the probe fiber and propagates the leaked light that has been propagated by the single mode core of the probe fiber;
A light receiving device that receives the leaked light received by the probe fiber directly from the probe fiber or through the dedicated single mode fiber, and measures the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light measured by the light receiving device;
An optical fiber side input / output device comprising: An optical fiber side input / output device that inputs and outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a dedicated double-clad fiber or a dedicated single-mode fiber;
A light-receiving device for a double-clad fiber that receives the leaked light propagating through the dedicated double-clad fiber connected to the optical switch and measures the light intensity of the leaked light;
A light receiving device for a single mode fiber that receives the leakage light propagating through the dedicated single mode fiber connected to the optical switch and measures the light intensity of the leakage light; and
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light measured by the light receiving device for double clad fiber or the light receiving device for single mode fiber;
An optical fiber side input / output device comprising: An optical fiber side input / output device that inputs and outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
One end can be connected to the other end of the probe fiber, and a dedicated single mode fiber that propagates the leaked light propagated by the single mode core of the probe fiber;
A connector capable of connecting the other end of the probe fiber or the other end of the dedicated single mode fiber;
A duplex optical transceiver that receives the leakage light coupled to the connector with a photodiode and outputs the light intensity of the leakage light; and
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit for causing the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver;
An optical fiber side input / output device comprising: An optical fiber side input / output device that inputs and outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a double-clad fiber relay path or a dedicated single-mode fiber;
A duplex optical transceiver that receives the leaked light propagating through the relay path of the double-clad fiber or the dedicated single-mode fiber with a photodiode and outputs the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit for causing the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver;
An optical fiber side input / output device comprising: An optical fiber side input / output device that inputs and outputs light through the bent portion with respect to a main optical fiber formed with a bent portion,
Leak which is a double clad fiber having a single mode core and a multimode core, one end of which is close to the bent portion, incident light is incident on the bent portion from the single mode core in the cross section of the one end, and leaks from the bent portion A probe fiber that receives light with a single-mode core and a multi-mode core at the cross section of the one end;
An optical switch for coupling the leaked light propagated by the probe fiber to a double-clad fiber relay path or a dedicated single-mode fiber;
A duplex optical transceiver that receives the leakage light propagated through the relay path of the double clad fiber with a photodiode and outputs the light intensity of the leakage light;
A light receiving device that receives the leaked light propagated through the dedicated single mode fiber and measures the light intensity of the leaked light;
An alignment mechanism for adjusting the position of the one end of the probe fiber;
A control circuit that causes the alignment mechanism to adjust the position of the one end of the probe fiber based on the light intensity of the leaked light output from the duplex optical transceiver or the light intensity of the leaked light measured by the light receiving device;
An optical fiber side input / output device comprising: The control circuit includes:
The position of the one end of the probe fiber is moved with respect to the alignment mechanism, the light intensity of the leaked light not passing through the dedicated single mode fiber is measured, and the leaked light with respect to the position of the one end of the probe fiber A first variation curve of the light intensity of
Moving the one end of the probe fiber to a first position which is the center of the full width at half maximum of the first fluctuation curve with respect to the alignment mechanism;
The position of the one end of the probe fiber is moved in the vicinity of the first position with respect to the alignment mechanism, the light intensity of the leaked light through the dedicated single mode fiber is measured, and the probe fiber Obtaining a second fluctuation curve of the light intensity of the leaked light with respect to the position of one end;
6. The optical fiber lateral entry according to claim 1, wherein the one end of the probe fiber is moved to a second position where the second fluctuation curve reaches a peak with respect to the alignment mechanism. Output device. The control circuit includes:
The optical fiber side input / output device according to claim 6, wherein the one end of the probe fiber is further moved to a third position that is a predetermined length away from the second position with respect to the alignment mechanism. A probe position alignment method for an optical fiber side input / output device according to claim 1,
A first fluctuation of the light intensity of the leaked light with respect to the position of the one end of the probe fiber is measured by moving the position of the one end of the probe fiber and measuring the light intensity of the leaked light not through the dedicated single mode fiber. A rough alignment step of obtaining a curve and moving the one end of the probe fiber to a first position which is the center of the full width at half maximum of the first fluctuation curve;
The position of the one end of the probe fiber is moved in the vicinity of the first position, the light intensity of the leaked light through the dedicated single mode fiber is measured, and the leaked light with respect to the position of the one end of the probe fiber A fine alignment step of obtaining a second variation curve of the light intensity and moving the one end of the probe fiber to a second position that is a peak of the second variation curve with respect to the alignment mechanism;
A probe position alignment method characterized by:

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