Composite optical fiber and method of the manufacturing of the same

A method of manufacturing a composite optical fiber, the method comprising:

• installing a plurality of elemental plastic optical fibers, each comprising a core portion and a cladding portion, inside of a plastic outer pipe,
• installing a plastic inner pipe to be generally centered within the plastic outer pipe,
• reducing an air pressure between the plastic outer pipe and the plastic inner pipe,
• heating and drawing the plastic outer pipe, the elemental plastic optical fibers, and the plastic inner pipe with a gap portion among the plastic outer pipe, the elemental plastic optical fibers, and the plastic inner pipe under a reduced-pressure condition, and
• installing an optical fiber in the plastic inner pipe after the heating and drawing.

A composite optical fiber comprising:

• a large-diameter optical fiber and
• small-diameter optical fibers,
• wherein diameters of the small-diameter optical fibers are smaller than a diameter of the large-diameter optical fiber,
• the large-diameter optical fiber is surrounded by the small-diameter optical fibers,
• the small-diameter optical fibers are plastic optical fibers each of the small-diameter optical fibers comprises a core portion and a cladding portion, and
• the small-diameter optical fibers have their cladding portions welded to one another.

A hollow optical fiber assembly, comprising:

• small-diameter optical fibers installed between a plastic outer pipe and a plastic inner pipe,
• wherein the small-diameter optical fibers are plastic optical fibers,
• each of the small diameter optical fibers comprises a core portion and a cladding portion, and
• the cladding portions are welded to one another.