METHODS FOR PRODUCING PREFORM AND OPTICAL FIBER

摘要

A method for producing a preform capable of restricting deformation of each member during a production process, and a method for producing, using the preform, an optical fiber small in polarization mode dispersion. In the method for producing the preform, a collapse process is divided into at least two steps; a first step of forming a first collapse body by the collapse of a core rod member and a first clad tube member and a second step of forming a new collapse body by the collapse of the first collapse body and a second clad tube member. An obtained collapse body is drawn in at least the first step; and such a multi-stage collapse process and drawing of an obtained collapse body can reduce an outer diameter ratio of an outer-side member to an inner-side member to be collapsed and hardly produce deformation that would be caused by heating and the like at one time collapse.