Optical fiber end processing method and optical fiber end processing apparatus

Abstract

There is provide an optical fiber end processing method, for processing an end portion of an optical fiber having a core and a clad surrounding the core, comprising: fixing two places of the optical fiber; firstly heating a part at a tip end side of the optical fiber between fixed parts fixed at two places, thereby melting the optical fiber at the heated part at the tip end side; secondly heating a part at a base end side of the optical fiber between the fixed parts away from the heated part at the tip end side in a state that the optical fiber is fixed at two places, thereby forming an expanded core region which is formed by expanding a diameter of the core by diffusing the dopant included in the optical fiber; and removing at least the heated part at the tip end side.

What is claimed is: 
     
         1 . An optical fiber end processing method, for processing an end portion of an optical fiber having a core and a clad surrounding the core, and added with a dopant on at least either the core or the clad, for making a refractive index of the core relatively larger than the refractive index of the clad, comprising the steps of:
 fixing the optical fiber and a supporting fiber, with each end face opposed to each other;   firstly heating the optical fiber and the supporting fiber so as to be fusion-spliced with each other after the fixing step;   secondly heating the optical fiber positioned away from the fusion-spliced part and positioned between a fixed part and the fusion-spliced part of the optical fiber in a state that the optical fiber and the supporting fiber are fixed, thereby forming an expanded core region which is formed by expanding a diameter of the core by diffusing the dopant after the firstly heating step; and   removing from the optical fiber by cutting, at least the fusion-spliced part after the secondly heating step.   
     
     
         2 . The optical fiber end processing method according to  claim 1 , wherein in the secondly heating step, a length of the expanded core region is expanded by moving a heating position of the optical fiber. 
     
     
         3 . The optical fiber end processing method according to  claim 1 , wherein a new end portion of the remaining optical fiber processed by the optical fiber end processing method of  claim 1 , is inserted into a ferrule and adhesion-fixed thereto, and thereafter an end face of the ferrule is polished, such that the expanded core region is positioned on the end face of the ferrule after polishing. 
     
     
         4 . An optical fiber end processing apparatus that processes an end portion of an optical fiber having a core and a clad surrounding the core, and added with a dopant on at least either the core or the clad, for making a refractive index of the core relatively larger than the refractive index of the clad, comprising:
 a fiber fixing unit that fixes two places of the optical fiber;   a heating unit that heats the optical fiber; and   a controller configured to control the heating of the optical fiber by the heating unit such that (i) a part at a tip end side of the optical fiber between fixed parts fixed at two places is heated, thereby the optical fiber at the heated part at the tip end side is melted, after the two places of the optical fiber are fixed by the fiber fixing unit, and (ii) a part at a base end side of the optical fiber between the fixed parts away from the heated part at the tip end side is heated in a state that the optical fiber is fixed at two places, thereby an expanded core region, which is formed by expanding a diameter of the core by diffusing the dopant, is formed after the optical fiber at the heated part at the tip end side is melted; and   removing unit that from the optical fiber by cutting, removes at least the heated part at the tip end side after the expanded core region is formed.   
     
     
         5 . An optical fiber end processing apparatus that processes an end portion of an optical fiber having a core and a clad surrounding the core, and added with a dopant on at least either the core or the clad, for making a refractive index of the core relatively larger than the refractive index of the clad, comprising:
 a fiber fixing unit that fixes the optical fiber and the supporting fiber respectively;   a heating unit that heats the optical fiber and the supporting fiber; and   a controller configured to control the heating of the optical fiber by the heating unit such that (i) the optical fiber and the supporting fiber is heated so as to be fusion-spliced with each other, after the optical fiber and the supporting fiber are fixed by the fiber fixing unit, and (ii) the optical fiber positioned away from the fusion-spliced part and positioned between a fixed part and the fusion-spliced part of the optical fiber is heated in a state that the optical fiber and the supporting fiber are fixed, thereby forming an expanded core region which is formed by expanding a diameter of the core by diffusing the dopant after the optical fiber and the supporting fiber is fusion-spliced; and   removing unit that from the optical fiber by cutting, removes at least the fusion-spliced part after the expanded core region is formed.