Method of manufacturing photonic crystal fiber using structure-indicating rods or capillaries

A method for manufacturing a photonic crystal fiber comprising a solid or hollow core and a cladding which surrounds the core and includes a plurality of pores extending along the core, the method comprising:

• forming a preform by packing in a support tube a core rod for forming the solid core and a plurality of capillaries for forming the cladding, or by providing a core space for forming the hollow core in the support tube and packing in a support tube a plurality of capillaries for forming the cladding;
• drawing the preform into a fiber under heating;
• and
• arranging a spacer formed of two or more spacer parts in the support tube such that the inner wall surface of the support tube has a substantially regular polygonal cross-sectional shape such that the core rod and the capillaries or the capillaries only are as closely packed as possible;
• the spacer includes two adjacent spacer parts and each of the two adjacent spacer parts includes a chipped part chipped parts for providing insertion holes which extend in the lengthwise direction thereof between the chipped parts;
• and
• structure-indicating rods or capillaries are fitted into the insertion holes between the chipped parts.