Abstract: A method for manufacturing a photonic crystal fiber including arranging a spacer formed of two or more spacer parts in a support tube such that the inner wall surface of the support tube has a substantially regular polygonal cross-sectional shape which allows closest packing of a core rod and a plurality of capillaries or the capillaries only; and forming a preform by packing in a support tube the core rod for forming a solid core and the capillaries for forming a cladding, or by providing a core space for forming a hollow core in a support tube and packing in the support tube a plurality of capillaries for forming the cladding; and drawing the preform into a fiber under heating.

Abstract: A method for manufacturing a photonic crystal fiber (20) including the steps of: arranging a spacer (4) formed of two or more spacer parts in a support tube (3) such that the inner wall surface of the support tube (3) has a substantially regular polygonal cross-sectional shape which allows closest packing of a core rod (2) and a plurality of capillaries (1) or the capillaries (1) only; and forming a preform (15) by packing in a support tube (3) the core rod (2) for forming a solid core and the capillaries (1) for forming a cladding, or by providing a core space for forming a hollow core in a support tube (3) and packing in the support tube (3) a plurality of capillaries (1) for forming the cladding; and drawing the preform (15) into a fiber under heating.

Abstract: A method for producing a silica glass optical fiber, which comprises coating carbon on the optical fiber with the use of the remaining heat of not less than 800.degree. C. possessed by the optical fiber just after heat wire drawing, for thermal decomposition of a carbon coat-forming gas comprised of one or more members selected from the group of halogenated hydrocarbons, hydrocarbons, and halogen molecules, which has 5 to 15 hydrogen atoms per 10 halogen atoms, and a reaction apparatus for coating carbon, wherein the area of the outer end of an exhaust region is greater than the transverse sectional area of a coating region, and the outer end is outwardly opened.