Optical fiber preform and method of manufacturing optical fiber

A method of manufacturing an optical fiber, the method comprising:

• drawing a glass optical fiber by heating and melting a tip portion of a taper portion of an optical fiber preform;
• and
• forming a coating on an outer circumference of the drawn glass optical fiber, wherein
• the optical fiber preform including:
• a columnar portion having an approximately constant radius of r;
• and
• the taper portion located adjacent to the columnar portion in a lengthwise direction and having a radius decreasing along the lengthwise direction,
• the taper portion includes:
• a first taper portion including a portion having a radius varying between 0.9r and 0.6r;
• and
• a second taper portion including a portion having a radius varying between 0.4r and 0.15r,
• a diameter of the first taper portion in the portion having the radius varying between 0.9r and 0.6r decreases so as to form a maximum angle θ1 between 40 degrees and 60 degrees with respect to the columnar portion,
• a diameter of the second taper portion in the portion having the radius varying between 0.4r and 0.15r decreases so as to form an average angle θ2 between 5 degrees and 30 degrees with respect to a central axis in the lengthwise direction, and
• a volume of the taper portion is smaller than or equal to 45% of a volume of a column having a same outer diameter as a maximum outer diameter of the taper portion and having a same length as the taper portion.