ACTIVE TEMPERATURE SENSOR USING SINGLE-MODE OPTICAL FIBER

An attempt was made to apply the single-mode optical fibers as a temperature sensor. The optical phase shifts were observed when the single-mode optical fiber was subjected to the temperature difference, ΔT, since the fiber length, the index of refraction and the core diameter changed as a function of temperature. An automatic phase detection device of the Mach-Zehnder fiber interferometer type was newly designed in order to detect the number of fringe shifts, from which the optical phase shifts was calculated. The sensitivity of temperature obtained using this device was in good agreement with the values calculated. Moreover, it was found that the temperature sensitivity of the bare fiber increased by the jacketing. These results indicated that the single-mode optical fiber was satisfactorily applied to a temperature sensor.