PURPOSE: To provide a dual core optical fiber which facilitates connection to an ordinary optical fiber and has high accuracy of temp. measurement by combining a core consisting of transparent glass and a core sealed with a liquid transparent material.
CONSTITUTION: This dual core optical fiber has the first core 12 consisting of the transparent glass in the central part of the clad 11 consisting of the transparent glass. The second core 13 is formed near this core by sealing the liquid transparent material into a through-hole formed in parallel with the first core 12. As a result, the first core 12 existing in the central part of the clad 11 is formed of the transparent glass and, therefore, this dual core optical fiber is easily fusion spliced to the ordinary single core optical fiber. The end face of the second core 13 consisting of the liquid transparent material is sealed by the clad end faces of the single core optical fiber connected thereto and, therefore, there is no need for specifically disposing a liquid sealing structure. Since the second core 13 is composed of the liquid transparent material having high dependency of optical characteristics (refractive index and scattering coefft.) on temp., the phase difference, etc., of light waves are made changeable in sensitive reaction with a temp. change.
IGARASHI MASARU
HORIMA HIROAKI
