Base material for optical fiber, optical fiber, and method for production thereof

A method for producing a base material for an optical fiber which comprises a step of binding at least two pieces of core base material (70) by fusion, to form one piece of core base material, a step of fusing a pair of glass rods (61, 62) for dummy to the both ends of a core base material (70), to form a starting material glass rod, a step of depositing fine glass particles generated by flame hydrolysis on the periphery of the starting material glass rod, to form a porous base material (80), and a step of converting the porous base material (80) to a transparent glass by sintering, to thereby form a base material (310) for an optical fiber containing a core portion and a clad portion; and a base material for an optical fiber produced by the above method.