Optical fiber and method for manufacturing optical fiber

An optical fiber comprising:

• a glass fiber including a core and a cladding;
• and
• a coating resin layer coating the glass fiber in contact with the glass fiber,
• wherein the coating resin layer has a primary resin layer coating the glass fiber in contact with the glass fiber and a secondary resin layer coating the primary resin layer,
• the primary resin layer comprises a cured product of a first resin composition containing a photopolymerizable compound and a phosphine oxide-based photopolymerization initiator,
• the secondary resin layer comprises a cured product of a second resin composition containing a photopolymerizable compound and a phosphine oxide-based photopolymerization initiator, and
• an amount of the phosphine oxide-based photopolymerization initiator remaining unreacted in the coating resin layer is 0.5 mass % or less, and
• wherein at least one of the first resin composition or the second resin composition contains nonylphenol polyethylene glycol acrylate as the photopolymerizable compound, and
• an amount of the nonylphenol polyethylene glycol acrylate remaining unreacted in the coating resin layer is less than 1.0 mass %.