METHOD OF PRODUCING PREFORM FOR DOUBLE CLAD OPTICAL FIBER AND METHOD OF PRODUCING DOUBLE CLAD OPTICA

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PROBLEM TO BE SOLVED : To provide a method by which a preform for a double clad optical fiber including a first clad having non-circular cross-section can be efficiently produced, and the double clad optical fiber is produced from the preform inexpensively. SOLUTION : In the method of producing the double clad optical fiber, quartz glass particulates are deposited on the outer circumference of a core preform to thereby form a porous preform, then the porous preform is made into transparent glass, thereby producing the preform for the double clad optical fiber, having a rare earth element-containing core and the first clad surrounding the circumference of the core, then the preform for the double clad optical fiber is wire-drawn, and a second clad is formed on the outer circumference of the first clad in the obtained optical fiber, thereby producing the double clad optical fiber. The method is characterized in that when the quartz glass particulates are deposited on the outer circumference of the core preform, the quartz glass particulates are deposited in such a manner that the cross-section of the obtained porous preform is made non-circular. COPYRIGHT : (C)2007, JPO&INPIT