OPTICAL FIBER FOR DETECTING GAS OR LIQUID AND DETECTION OF GAS OR LIQUID BY USING THE OPTICAL FIBER

摘要

PURPOSE:To provide the optical fiber for detecting gas or liquid capable of detecting even a material having the refractive index lower than the refractive index of quartz and the method for detection of the gas or liquid by using this optical fiber. CONSTITUTION:This optical fiber for detecting gas or liquid is constituted by disposing a core 2 having the refractive index higher than the refractive index of a clad 1 in an eccentric position near the outer periphery of the clad 1. A primary coating layer 3 having nearly the same refractive index as the refractive index of the clad 1 is formed on the outer periphery of the clad 1. Light waves of the same wavelength as the absorption wavelength intrinsic to gas or liquid is used as the light wave propagating in the optical fiber 4 for detecting gas or liquid in the case of detection of the sticking of gas or liquid by this optical fiber 4.