Optical fiber preform production method, optical fiber preform, and optical fiber production method

An optical fiber preform comprising:

• a cladding glass body that is a cladding of an optical fiber, is cylindrical, and comprises inner holes along an axial direction;
• glass rods that are cores of the optical fiber, and that are each accommodated in a respective one of the inner holes;
• a connecting glass tube fixed to a first end the cladding glass body;
• and
• a single dummy silica rod that abuts the first end of the cladding glass body, that is accommodated inside of the connecting glass tube, and that is fixed to the connecting glass tube, wherein
• in the first end of the cladding glass body, a first end of the inner holes are closed by the single dummy silica rod and the connecting glass tube,
• in a second end of the cladding glass body opposite to the first end of the cladding glass body, a second end of the inner holes are closed by a tip seal.