Glass preform and method of producing the same

摘要

In a glass preform (10) to be subjected to fiber-drawing, use is made of a cylindrical glass tube (21) whose one end in an axial direction is sealed. A plurality of glass capillaries (22) extend in the glass tube in the axial direction. The glass capillaries are fused to one another into an integral structure. The glass capillaries have air holes periodically arranged on a plane perpendicular to the axial direction, respectively.