Optical fiber provided with synthetic resin coating and its production

PURPOSE: To prevent optical transmission loss arising from microbending by specifying the thickness of the first layer and modulus of elasticity of the second layer of an optical fiber having a synthetic resin coating consisting of the first sheath layer of synthetic rubber and the next synthetic resin sheath layer having the modulus of elasticity larger than the modulus of elasticity of the first layer. CONSTITUTION: A glass fiber 1 is provided with a soft buffer layer 2 consisting of the synthetic rubber having the modulus of elasticity of 0.1 to 10MPa right after the formation of this glass fiber. The first layer 2 is provided thereon with the solid upper layer 3 consisting of the second synthetic resin having the modulus of elasticity larger than the modulus of elasticity of the first layer in order to protect the soft buffer layer 2 during the execution of another treatment. The thickness of the first layer 2 is specified to 5 to 20μm and the modulus of elasticity of the second layer 3 to ≥1000MPa. The modulus of elasticity of the second layer which exhibits a high value has an advantage in the mechanical resistance force of the optical fiber. As a result, the optical transmission loss occurring in the microbending is prevented. COPYRIGHT: (C)1989,JPO