Reticulated tube, optical fiber protective unit, method for protecting optical fiber, and method for manufacturing reticulated tube

1. An optical fiber protective unit comprising:

a reticulated tube; and

a tubular member that is inserted through the reticulated tube and that is configured to accommodate a plurality of optical fibers, wherein

the reticulated tube is disposed on an outer periphery of the tubular member in a state folded in a longitudinal direction,

both end parts of the reticulated tube are located on the outer periphery of the tubular member, and

the reticulated tube in an extended state is longer than the tubular member.

2. The optical fiber protective unit according to claim 1 , wherein

one of the end parts of the reticulated tube is temporarily fixed to the tubular member.

3. The optical fiber protective unit according to claim 1 , wherein

there is exactly one said reticulated tube disposed on the outer periphery of the tubular member.

4. The optical fiber protective unit according to claim 1 , wherein

the tubular member is slidable with respect to the plurality of optical fibers.

5. The optical fiber protective unit according to claim 1 , wherein

when the reticulated tube is extended, an inner diameter of the reticulated tube does not decrease.

6. The optical fiber protective unit according to claim 1 , wherein

L1/L0 is less than or equal to 0.13,

where

L0 is a length of the reticulated tube before contraction in the longitudinal direction, and

L1 is a length of the reticulated tube after contraction in the longitudinal direction.

7. An optical fiber protective unit comprising:

a reticulated tube; and

a tubular member that is inserted through the reticulated tube and that is configured to accommodate a plurality of optical fibers, wherein

the reticulated tube is disposed on an outer periphery of the tubular member in a state folded in a longitudinal direction,

both end parts of the reticulated tube are located on the outer periphery of the tubular member,

wires constitute the reticulated tube, and

an intersection angle of the wires is not variable.

8. An optical fiber protective unit comprising:

a reticulated tube; and

a tubular member that is inserted through the reticulated tube and that is configured to accommodate a plurality of optical fibers, wherein

the reticulated tube is disposed on an outer periphery of the tubular member in a state folded in a longitudinal direction,

both end parts of the reticulated tube are located on the outer periphery of the tubular member,

the reticulated tube in a folded state is extendable in the longitudinal direction by pulling out one of the end parts of the reticulated tube from the tubular member

an opening of one of the end parts of the tubular member is widened, and

an outer diameter of the end part having a widened opening is greater than the inner diameter of the reticulated tube in the folded state.

9. A method for protecting an optical fiber, the method comprising:

preparing an optical fiber protective unit comprising

a reticulated tube, and

a tubular member inserted through the reticulated tube that is in a state folded in a longitudinal direction, such that the reticulated tube is disposed in a folded state on an outer periphery of the tubular member;

inserting a plurality of optical fibers into the tubular member, and thereby inserting the plurality of optical fibers into the reticulated tube in the folded state;

pulling out an end part of the reticulated tube from the tubular member; and

extending the folded-state reticulated tube in the longitudinal direction, to thereby insert the plurality of optical fibers into the reticulated tube in an extended state.

10. The method for protecting an optical fiber according to claim 9 , wherein,

after pulling out the end part of the reticulated tube from the tubular member, the tubular member, which has the reticulated tube disposed on the outer periphery thereof, and the plurality of optical fibers are caused to slide relative to one another, to thereby insert the plurality of optical fibers into the reticulated tube.

11. The method for protecting an optical fiber according to claim 10 , wherein,

after pulling out the end part of the reticulated tube from the tubular member, the tubular member, which has the reticulated tube disposed on the outer periphery thereof, is caused to slide with respect to the plurality of optical fibers, to thereby insert the plurality of optical fibers into the reticulated tube.

12. The method for protecting an optical fiber according to claim 11 , wherein

the optical fibers extend out from a lead part of an optical cable, and

the end part of the reticulated tube, which has been pulled out from the tubular member, is fixed to the lead part of the optical cable.

13. The method for protecting an optical fiber according to claim 10 , wherein,

after pulling out the end part of the reticulated tube from the tubular member, the optical fibers, together with the pulled-out end part, are caused to slide with respect to the tubular member, which has the reticulated tube disposed on the outer periphery thereof, to thereby insert the plurality of optical fibers into the reticulated tube.

14. The method for protecting an optical fiber according to claim 10 , wherein

the tubular member, which has the reticulated tube disposed on the outer periphery thereof, is fixed in a state where the plurality of optical fibers are inserted into the reticulated tube, which has been pulled out from the tubular member and extended.

15. The method for protecting an optical fiber according to claim 14 , wherein

the plurality of optical fibers constitute an optical fiber group from a single optical cable.

16. The method for protecting an optical fiber according to claim 14 , wherein

a plurality of optical fiber groups branch from a single optical cable, and

one or more of the optical fiber groups branching from the single optical cable are inserted through a respective one of the tubular member and the reticulated tube.

17. The method for protecting an optical fiber according to claim 16 , wherein

an end part of the optical cable is fixed to a first fixing part of a branch unit; and

the tubular member is fixed to a second fixing part of the branch unit that is different from the first fixing part.