Optical fiber

An optical fiber comprising:

• a glass fiber including a core and a cladding;
• and
• a coating resin layer coating an outer periphery of the glass fiber,
• wherein the coating resin layer includes:
• a primary resin layer coating the outer periphery of the glass fiber;
• a secondary resin layer coating an outer periphery of the primary resin layer;
• and
• a coating layer coating an outer periphery of the secondary resin layer,
• the glass fiber has an outer diameter of from 124 μm to 126 μm,
• the secondary resin layer has an outer diameter of from 145 μm to 165 μm,
• the coating layer has an outer diameter of from 155 μm to 175 μm,
• the primary resin layer has a thickness of 5 μm or more,
• the secondary resin layer has a thickness of 5 μm or more,
• the primary resin layer has an in situ elastic modulus of from 0.1 MPa to 0.4 MPa,
• the secondary resin layer has an in situ elastic modulus of from 1500 MPa to 2800 MPa, and
• a maximum value of amplitude of an amount of eccentricity is 4 μm or less in a spectrum obtained by measuring, at a plurality of measurement points set at predetermined intervals in an axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis relative to the outer periphery of the secondary resin layer, the amount of eccentricity being measured based on a position of an outer periphery of the coating resin layer and a position of the outer periphery of the glass fiber that are obtained from an image of light penetrated through the optical fiber and by applying Fourier transform to a waveform representing the amount of eccentricity at each position of the plurality of measurement points,
• a wavelength at which the amplitude of the amount of eccentricity is largest is 0.1 m or more.