JPH09258034A - Optical branching module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the working space for drawing out of optical fiber to improve the packaging density and to lessen the influence to be exerted on optical communication at the time of switching the connection, etc., by providing an optical branching module with a movable extra length housing section which houses a connector for switching and connected extra lengths and from which the connected extra lengths are led out as leading-out extra lengths at the time when this housing section is parted from a main body. SOLUTION: At this time of switching the connection at the MT connector 26, the movable extra length housing section 27 is led out to the outer side of the station and the MT connector 26 is taken out together with optical fiber ribbons 8a, 8b, 25 connected to the MT connector 26. The switching work is then carried out. At this time, a disk 40 is made rotatable with a circular recessed part 41. Then, the connected extra length 25a of the optical fiber ribbon 25 mounted on the outer side of a mandrel 44 rotating according to the leading out of the movable extra length housing section 27 is led out and functions as the leading-out extra length. The connected extra length 25a unwound in such a manner is held anchored by a cord anchoring implement 37a and, therefore, tensile force does not act on the optical fiber ribbon 25 housed in the main body 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical branch module for inserting test light into an optical fiber for communication.

[0002]

2. Description of the Related Art In an optical fiber network, for example, in order to branch and connect an optical cable to an optical fiber core by connecting an optical connector, an optical wiring rack is used which terminates a large number of internal and external optical fibers to form a large group. It In particular, as an optical wiring rack used for a subscriber transmission line, an FTM (Fib
er Termination Module) is used. 3 and 4 are views showing a conventional optical wiring rack applied to FTM, in which reference numeral 1 is a frame, 2
Is a terminal board, 3 is an optical connector, and 4 is an optical branching module.

[0003] The frame 1 is formed in a shelf shape divided into a plurality of steps at equal intervals by horizontally arranged partition plates 5, and a plurality of steps for accommodating the optical branching module 4 are formed. . A terminal plate 2 that substantially covers the opening is fixed to the same side opening of each stage of the frame 1.
The terminal board 2 has a hole 6 for mounting the optical connector 3.
2 are arranged side by side, and two well-known SC type optical connectors 3 are arranged and fixed in the hole 6. The optical connector 3 has a plurality of SC type terminals (not shown) to which the intra-station optical fiber core wire 7 is connected on the outside, and a plurality of SC type terminals (not shown) to which the outside optical fiber core wire is connected on the inside. It is arranged at a position corresponding to the terminal for the optical fiber core wire 7.

The basic configuration of the optical branching module 4 is shown in FIG. 7 below. As shown in FIG. 7, in the optical branching module 4, the optical coupler 9, the optical filter 4d, and the optical fiber 4 are provided.
Optical components such as the optical connector 10 for switching and connecting c are stored. To test and manage the optical line, first
The optical branching module that accommodates the core wire to be tested is selected by the core wire selection device 4a, and the test light (light pulse) sent from the optical pulse test device 4b is used as the measurement target via the optical coupler 9. Is transmitted to the optical fiber 4c outside the station, and the backscattered light generated in the optical fiber 4c is received by the light receiving section of the optical pulse test apparatus 4b via the optical coupler 9, and then the received backscattered light is received. By analyzing the waveform of the light, the loss abnormality of the optical line is monitored.

A conventional 4-core branching module will be described with reference to FIGS. 5 and 6. This optical branching module is a thin-plate package as a whole, and can be opened and closed by an opening / closing lid (not shown). On the rear surface side (left side of FIG. 5 and FIG. 6) of the optical branching module 4, a four-core optical fiber tape 8a led out from an external optical cable (termination cable) K
Then, one 8-core optical fiber tape 8b derived from the core selection device is introduced. In the optical branching module 4,
Four fiber type optical couplers 9 are housed, and the optical fiber tape 8b on the side of the optical fiber selecting device is connected to the optical fiber tape on the side of the optical coupler 9 by the 8-core MT connector 10.

Next, the optical fiber tape 8a on the outside optical cable (termination cable) side is connected to the optical fiber tape (not shown) on the optical coupler 9 side by the 4-core MT connector 10. On the other hand, one 4-core optical fiber tape led out from the station inner side port of the optical coupler 9 is led out to the outside of the package as an optical cord 8w, and further, in the multi-core single-core branching device F fixed to the side plate. It is branched to the single-core optical fiber 8y. The tip of each branched single-core optical fiber 8y is SC
And is connected to an SC type optical adapter 3 fixed to the terminal plate 2 of the frame 1.

[0007] About 50 optical branching modules 4 are provided in each stage of the frame 1 with a width of, for example, 13.5 mm. Inside the optical branch module 4, an optical cord 8w, an optical coupler 9 connected to the optical cord 8w,
The MT connector 10 (Mecha) that optically connects the optical fiber tapes 8a and 8b and the optical cord 8w so that the connection can be switched.
and a physically transferable). A suspending member 12 for suspending from a suspending rail 11 erected above each step of the frame 1 is attached to the upper side when the optical branching module 4 is stored.

[0008]

By the way, in the case of the optical branching module 4 as described above, the number of parts is large, and it is sufficient for each stage in view of the demand for an increase in the number of core wires to be accommodated and a higher packaging density. Since the space is not secured, the work of mounting the optical components such as the optical connector 3 has to be performed in a narrow space, and the workability is extremely poor. Further, even when a specific one optical branching module 4 is replaced, it is necessary to remove the optical branching module 4 in the vicinity of the optical branching module 4 to secure a space where an operator can reach. Work has become difficult as the density has increased.

That is, when the optical fiber switching connection system is used to switch the MT connector 10 housed in the optical branching module 4 at the time of switching the cores, as shown in FIG. 4 is pulled out from the frame 1 and placed on the shelf, the inside of the pulled out optical branching module 4 is opened, and the MT connector 1
0 is pulled out, but when the MT connector 10 in the optical branching module 4 is pulled out, the optical components such as the optical coupler 9 and the filter (not shown) connected to the optical cord 8w and the like are also pulled out together. In the line state, it was difficult to work without affecting the optical communication.

In the above-mentioned optical wiring rack, there is a demand for further improvement in packaging density as the number of accommodated core wires increases. However, the space between the optical branching modules for pulling out the optical branching module 4 and the MT Since it is necessary to secure a work place for switching the connection with the connector 10, there is a limit to the improvement of the mounting density.

The present invention has been made in view of the above-described problems, and it is possible to reduce the work space for pulling out the optical branching module and to improve the mounting density, and to switch the connection. An object of the present invention is to provide an optical branching module that can reduce the influence on optical communication during work as much as possible.

[0012]

SUMMARY OF THE INVENTION In an optical branching module of the present invention, a main body for supporting an optical connector for branching connection at one end and accommodating an optical fiber having an optical coupler in the middle, and an optical fiber between them. The switch connector for connecting the switch and the connection extra length are housed, and are provided so that they can be retracted at the end of the main body that faces the optical connector for branch connection, and the extra connection length is pulled out when separated from the main body. A movable extra length storage portion that is pulled out as a long length is provided, and an optical fiber that is pulled out from the movable extra length portion is connected to an optical switch that is arranged on the lower side of the main body, which is the means for solving the above problems. As an operation of the optical branching module of the present invention, the movable extra length storage portion is pulled out from the main body and the switching optical connector is switched, and other optical components in the movable extra length storage portion are replaced and maintained. By doing this,
Since it is not necessary to pull out the main body, it is possible to perform work without affecting the optical components inside the main body or the optical components inside the adjacent optical branching module, and it is easy to re-store the pulled out switching optical connector. . Further, when the movable extra length storage section is pulled out from the main body, the optical fiber pulled out from the movable extra length storage section functions as the extra drawing length.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. Reference numeral 20 in the figure
Is the optical branching module of the present embodiment. In the figure, the same components as those in FIGS. 3 to 7 are designated by the same reference numerals,
The description will be simplified. The optical branching module 20 is shown in FIG.
And is housed in the frame 1 shown in FIG.

As shown in FIGS. 1 and 2, the optical branching module 20 is constructed so that it can be supported at a fixed position in the frame 1 via a supporting means 21, and at the time of the supporting, the frame 1 is supported.
An optical connector 23 for branch connection to the in-station device side is installed at one end 22 facing the outside, and a plurality of four- or eight-fiber optical fiber tapes 25 (multicore optical fiber) connected to the optical connector 23 for branch connection are connected. Fiber) and the optical fiber tape 25
A thin plate-shaped main body 24 for accommodating optical components such as an optical coupler 28 and a branch portion 29 which are interposed in the middle of the optical fiber, and an optical cable K.
The optical fiber tapes 8a and 8b (optical fibers) derived from the optical fiber tape 25 and the optical fiber tape 25 are switchably connected to each other, and the MT connector 26 and a connection extra length 25a thereof are housed therein. A movable surplus length storage portion 27 is provided at an end portion facing the optical connector 23 so as to be retractable and retractable, and a connection surplus length 25a is pulled out when it is separated from the main body 24 and functions as a withdrawal surplus length.

The main body 24 is made of a lightweight material such as plastic and is a bottomed rectangular tubular body having a rectangular plate shape when viewed from the outside.
The support means 21 is provided at a portion of one end face of the rectangular shape of the main body 24 in the short side direction near the branch connection connector 23.
The hanging tool 30 (21) is attached as. The suspending tool 30 engages with an engaging part (not shown) provided on the upper partition plate 5 in the frame 1 where the optical branching module 20 is arranged from the outside (left side in FIG. 1) of the main body 2 by engaging the engaging part (not shown).
4 in a predetermined direction (perpendicular to the terminal board 2 and the partition board 5
Positioned in a plane perpendicular to the plane). In addition, hanging equipment 3
The position of 0 is not limited to the illustrated position. Further, the supporting means 21 may have any other structure than the hanging tool 30 as long as the main body 24 can be positioned in the predetermined direction.

An end face plate 31 for supporting the branch connection connector 23 is provided at one end 22 of the main body 24. A connector support hole 32 is opened in the upper portion (upper side in FIG. 1) of the end plate 31. This connector support hole 32
A connector 23 for branch connection is fitted in the end face plate 31 with a connecting axis line for optically connecting the optical fiber cores to each other. An anti-sway pin 31a that prevents the optical branching module 20 inserted in the frame 1 from swinging around the suspending tool 30 is provided on the local inner end surface of the end face plate 31.

The branch connection connector 23 is a multi-core SC type optical adapter having a built-in positioning ring sleeve, and is an SC plug that terminates the tip of the optical fiber tape 25 branched by the branch portion 29. 23a can be attached and detached. The branching unit 29 is configured to fuse a single-core optical fiber to the optical fiber tape 25 output from the optical coupler 28 to branch a multi-core single fiber. An SC plug 23b terminating the optical fiber 7 inside the station is inserted into the connector 23 for branch connection so as to be insertable and removable from the outside. The optical coupler 28 is a substrate waveguide type and has an optical filter built therein.

A plurality of radius maintaining projections 33 are provided on the inner wall surface of the main body 24 so as to bend and store the extra length of the optical fiber tape 25 while maintaining a radius larger than a specified radius. These radius maintaining protrusions 33 are provided on the optical fiber tape 25.
It is an arc-shaped flange curved with a radius that allows it to be curved with a radius larger than the specified radius, and is continuously arranged in a line on the inner wall surface of the main body 24. Optical component supporting portions 34 for supporting the optical coupler 28 and the branch portion 29 are provided on both sides of the region where the radius maintaining protrusions 33 are continuously provided.

A guide portion 35, which guides the movable extra length storage portion 27 and is slidable along the longitudinal direction of the main body 24, is provided at the outer end of the main body 24 so as to project. There is. The guide portion 35 is a portion in which one side portion in the cross-section direction of the main body 24 is projected to the outside of the main body 24. The upper end portion (upper side in FIG. 1) of the guide portion 35 is slidably movable while being engaged with an engaging portion (not shown) provided in the movable extra length storage portion 27 to suspend the movable extra length storage portion 27. A rail 36 is provided that is supported on the outside of the guide portion 35 so that the rail 36 can project and retract outside the local area of the guide portion 35.

At the base end portion of the guide portion 35, there is provided a regulation plate 37 for regulating the movement of the movable extra length storage portion 27 to the inside of the station. The regulation plate 37 is located at a substantially central portion in the longitudinal direction of the main body 24, extends in the thickness direction of the main body 24, and
4 defines a surplus length storage portion 38 capable of storing the surplus length of the optical fiber tape 25. A cord retainer 37 a for retaining the optical fiber tape 25 is attached to the extra length storage portion 38 side of the regulation plate 37.

At the outer end of the guide portion 35, the main body 24 is provided.
A positioning member 35a made of resin is provided so as to position the main body 24 in the insertion direction when the frame 1 is inserted from the outside of the frame 1 toward the inside of the frame. Positioning member 3
When the main body 24 is inserted into the frame 1, the tip 5a is inserted into a stop hole (not shown) of the frame 1 to position the main body 24 with respect to the frame 1. Positioning member 35a inserted in the stop hole
Is further pressed into the stop hole to expand the diameter of the tip, and is temporarily fixed to the frame 1. The positioning member 35a can also be used as a pull-out knob for pulling out the main body 24 inserted into the frame 1 to the outside of the frame 1.

The movable surplus length storage portion 27 is rotated by a rectangular substrate 39 movably suspended on a rail 36 of the guide portion 35 and an axis line perpendicular to the substrate 39 at the central portion of the substrate 39. And a circular disc 40 that is freely provided. The substrate 39 is the guide portion 3
5 is a rectangular plate having a size that can be accommodated in 5, and has a circular concave portion 41 in the center thereof, in which the disc 40 can be rotatably accommodated. The discs 40 abut one another via diametrically extending grooves 42.
It has one semicircular portion 43. At the center of each semi-circular portion 43, the optical fiber tapes 8a and 8b mounted on the outside thereof are provided.
A substantially elliptical mandrel 44 that maintains the radius of curvature of is bulged. Each of the semi-circular portions 43 is provided between the inner peripheral surface of the circular recess 41 and the outer peripheral surface of the mandrel 44.
A and 8b are accommodated while maintaining a bending radius larger than the specified value. A connector support part 45 for sandwiching and supporting the MT connector 26 is provided at the center of the groove 42.
Is provided.

The circular plate 40 is the circular recess 4 of the substrate 39.
1 covers more than half of the outer peripheral surface of the disc 40, and moreover, the outer peripheral surface is engaged with the inner peripheral surface of the circular recess 41 by a projection and a groove (not shown) extending in the circumferential direction. The circular recess 41 does not fall off. Since the lower portion of the disc 40 is exposed below the circular recess 41, the optical fiber tape 8 is exposed by utilizing this exposed portion.
The a and 8b can be easily mounted. Also,
The optical fiber tapes 8a and 8b mounted on the disc 40 are
The lid 40a is detachably attached to the outer surface of the disc 40 so that the disc 40 does not protrude to the outside of the disc 40. The circular plate 40 may have an elliptical shape or the like other than the perfect circular shape. Further, the disc 40 and the circular recess 41 may have a shape in which the range of relative rotation is set.

In the illustrated optical branching module 20, one coded optical fiber tape 8 is used.
a and two optical fiber tapes 8b are introduced.
These optical fiber tapes 8a and 8b are switchably connected to the optical fiber tapes 25 having the same number of cores via a 4-core or 8-core MT connector 26, respectively. MT
The extra connection length 25 a of the optical fiber tape 25 generated when the connector 26 is supported by the connector support portion 45 is wound around the outer peripheral surface of the mandrel 44 and is stored in the movable extra length storage portion 27. Three optical fiber tapes 25 are required.
Also, three MT connectors 26 are required. The optical fiber tape 25 is connected to each of the MT connectors 26.

Each of the optical fiber tapes 8a and 8b is adapted to be pulled out below the movable extra length storage portion 27. The optical fiber tape 8a is a gutter-shaped code guide 4 arranged below the main body 24 in each stage of the frame 1.
6 is wired and is guided to the side portion of the frame 1. The optical fiber tape 8b is attached to the main body 2 at each stage of the frame 1.
4 is wired to the optical switch 47 arranged below. The optical fiber tapes 8a and 8b are adapted to be wound and unwound by the rotation of the mandrel 44 below the movable extra length storage portion 27.

The optical fiber tape 25 has an extra length storage section 38.
The optical fiber core wire 7 is housed by being bent by a radius maintaining projection 33 with a radius larger than a predetermined radius and accommodated, and passing through an optical coupler 28 and a branch portion 29 interposed in the middle, and via the branch connection connector 23. And is switchably connected. As the branch connection connector 23, a 4-core connector is used in two lines.

In the optical branching module of the present invention, a plurality of optical fiber tapes 8a and 8b introduced from the outside of the station are switchably connected to the optical fiber tape 25 through the MT connector 26 in the movable extra length storage section 27. At the same time, the optical fiber tape 25 is switchably connected to the intra-office optical fiber core wire 7 via the branch connection connector 23 to which the single-branched end of the optical fiber tape 25 is connected.
The extra length of the optical branching module 20 is stored in the extra length storing portion 38 while maintaining the bending radius larger than the specified value, and the optical branching module 20 is stored at an appropriate position of the frame 1. The extra connection length 25 a of the MT connector 26 of the optical fiber tape 25 is mounted on the outer peripheral portion of the mandrel 44 and stored.

Optical branching module 2 housed in frame 1
0, in order to switch the connection at the MT connector 26, the movable surplus length storage portion 27 is pulled out to the outside of the main body 24 and the MT connector 26 is connected to the optical fiber tapes 8a and 8b. , 25, and perform switching work. At this time, since the disc 40 is rotatable with respect to the circular recess 41, the disc 40 is rotated as the movable surplus length storage 27 is pulled out and is rotated.
4. A connection extra length 25a of the optical fiber tape 25 mounted on the outside is unwound and functions as a pull-out extra length. Since the unwound connection extra length 25a is retained by the cord retainer 37a, no tensile force acts on the optical fiber tape 25 housed in the main body 24, and the optical components in the main body 24 are not affected. Work can be performed efficiently without affecting. At this time, the optical fiber tapes 8a and 8b are attached to the cord guide 46 and the optical switch 4 respectively.
Since the movable extra length storage portion 27 is pulled out, it is unwound below the movable extra length storage portion 27 as the movable extra length storage portion 27 is pulled out.

When the MT connector 26 is stored again, the disc 40 is rotated so that the extra length of the optical fiber tapes 8a, 8b, 25 connected to the MT connector 26 is wound around the outer peripheral surface of the mandrel 44. To wear. By doing so, the optical fiber tapes 8a, 8b, 25 can be efficiently re-stored without being entangled with each other. In the branch connection connector 23, the intra-office optical fiber core wire 7 is replaced, or the optical branch module 20 is pulled out from the frame 1 and the SC plug 23a of the optical fiber tape 25 is replaced with the branch connection connector 23. further,
In order to insert / remove the optical branching module 20 into / from the frame 1, the optical branching module 2 is used by using the positioning member 35a.
Move 0 relative to frame 1.

Therefore, the optical branching module 2 of the present invention
According to No. 0, the optical fiber tapes 8a and 8b wired to the cord guide 46 and the optical switch 47 are unwound from the mandrel 44 below the movable extra length storage portion 27, so that the cord guide is wound. 46 and optical switch 4
7 can be arranged close to the main body 24, and space can be saved. As a result, the packaging density of the optical branch module 20 and the optical switch 47 in the optical wiring rack is improved. Further, the introduction position of the optical fiber tapes 8a and 8b into the movable extra length storage section 27 is always below the movable extra length storage section 27, and these optical fiber tapes 8a and 8b project rearward of the optical branching module 20. Therefore, the optical fiber tapes 8a and 8b are arranged and wired on the back side of the optical wiring rack without interfering with each other, and work efficiency such as connection switching is improved.

Further, since the optical branching module 20 can store a plurality of optical fiber tapes 8a, 8b, 25 in a space-saving manner, the mounting density is improved and the movable extra length storing portion 27 is provided in the main body 24. Against,
The extra length of the optical fiber tapes 8a, 8b, 25 and the optical components such as the MT connector 26 can be integrally drawn out and re-stored only by re-storing, and it is not necessary to pull out the main body 24 at the time of connection switching in the MT connector 26 Body 24
The work can be performed without affecting the internal optical components and the optical components in the adjacent optical branching module 20, and the extracted optical components can be easily stored again. As a result, it becomes possible to switch the connection between the optical fiber tapes 8a and 8b and the optical fiber tape 25 in a live state.

Further, by adopting the rotatable disc 40 in the movable extra length storage section 27 that can be pulled out to the outside of the station, it is not necessary to install a space for storing the extra extension length of the movable extra length storage section 27. , The size of the frame 1 in the depth direction can be reduced, and the optical fiber tapes 8a, 8b,
The mounting density of the connector 25 and the connector 23 for branch connection is further improved. In addition, since it is not necessary to secure a work space for connection switching between the adjacent optical branching modules 20 in the optical wiring rack, it is possible to install the optical branching modules 20 close to each other and to install the optical fiber in the optical wiring rack. Branch module 2
It is possible to provide an optical wiring rack which can improve the packaging density of 0 and can cope with the optical cable K having more cores.

The optical branching module of the present invention can be applied to an optical wiring board, an optical termination box, etc. other than the optical wiring rack.

[0034]

As described above, according to the optical branching module of the present invention, a main body for supporting an optical connector for branch connection at one end and accommodating an optical fiber having an optical coupler interposed therein is provided. , A switching connector for connecting the optical fibers to each other in a switchable manner and a connection extra length thereof are housed, and are provided so as to be retractable at an end portion of the main body facing the branch connection optical connector, and a connection extra when separated from the main body. A movable surplus length storing portion whose length is pulled out as a pull-out surplus length, and an optical fiber pulled out from the movable surplus length portion is connected to an optical switch arranged on the lower side of the main body, and the optical switch is connected to the main body. Since they can be placed close to each other, the installation space for the main unit and the optical switch can be saved, and the introduction position of the optical fiber to the movable extra length storage section is always movable extra extra length. Since these optical fibers do not project to the rear of the optical branching module below the section, the optical fibers are arranged and wired without interference in the vicinity of the movable extra length storage section, and the work efficiency of connection switching etc. is improved. Such an excellent effect.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of an optical branching module of the present invention.

FIG. 2 is a perspective view showing the optical branching module of FIG.

FIG. 3 is a side view showing an optical wiring rack.

FIG. 4 is a front view showing an optical wiring rack.

FIG. 5 is a side view showing a conventional optical branching module.

FIG. 6 is a diagram showing a conventional optical branching module,
It is a side view which shows the connection switching in MT connector.

FIG. 7 is a schematic diagram showing a basic configuration of an optical branching module.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Frame, 7 ... Optical fiber core wire (intra-office optical fiber core wire), 8a ... Optical fiber tape, 8b ... Optical fiber tape, 20 ... Optical branch module, 21 ... Supporting means, 22 ...
End portion, 23 ... Branch connection connector, 24 ... Main body, 25 ...
Optical fiber tape, 25a ... Connection extra length, 26 ... Switching connector (MT connector), 27 ... Movable extra length storage section, 28
... optical coupler, 30 ... supporting means (hanging tool), 47 ... optical switch.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Ryuji Mima 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Masato Kuroiwa 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Naoki Nakao 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Takashi Ebihara 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. within Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. An optical branching module (20) for branching and connecting a multi-core optical fiber (8a, 8b) to an optical fiber core wire (7) by an optical connector connection, the branching optical connector (23). ) Is supported at one end (22), and a main body (24) for accommodating an optical fiber (25) having an optical coupler (28) interposed therein, and a switching connector for connecting the optical fibers to each other (26)
And a connection extra length (25a) of the main body, which is provided so as to be retractable at an end of the main body facing the optical connector for branch connection, and the extra connection length is pulled out as a draw extra length when separated from the main body. An optical branching module comprising a long storage part (27), and an optical fiber drawn from the movable extra length part is connected to an optical switch (47) arranged on the lower side of the main body.