Optical fiber bundle structure, optical connector, optical fiber connection structure, and method of manufacturing optical fiber bundle structure

An optical fiber bundle structure, comprising:

• plural optical fiber core wires;
• a crossing preventing member having the plural optical fiber core wires inserted through the crossing preventing member along a longitudinal direction;
• and
• a grasping member that applies a grasping force to the crossing preventing member, wherein
• the plural optical fiber core wires have, in order from a leading end of the plural optical fiber core wires, a glass fiber portion, and a resin coated portion having resin coated on glass fibers,
• the glass fiber portion has, in order from a leading end of the glass fiber portion, a small diameter portion, a tapered portion, and a large diameter portion,
• the crossing preventing member has slits formed therein, the slits each having a width with a width's center at a point equally dividing one of sides of an approximate polygon circumscribing the plural optical fiber core wires, by a number of the optical fiber core wires that are in contact with that side in a cross section of the crossing preventing member, the cross section being orthogonal to the longitudinal direction, the slits extending from a leading end of the crossing preventing member to a midway point closer to a trailing end of the crossing preventing member,
• each vertex of the approximate polygon circumscribing the plural optical fiber core wires has a curved shape, and
• the sum of the widths of the slits positioned at the respective sides is equal to or larger than a difference between:
• a length of a shortest perimeter surrounding the plural optical fiber core wires at a hindmost end portion of the slits at the trailing end;
• and a length of a shortest perimeter surrounding the plural optical fiber core wires at the leading end.