Measurement of temperature with optical fibers

A theoretical study has been made of temperature effects on light propagation in optical fibers to determine their applicability as temperature sensors for remote measurements in locations such as large electrical machinery. It is found that propagation and loss characteristics of fibers can be altered by temperature in several ways, any of which may be used as the basis for a monitoring device. Coupling between adjacent fibers may also be influenced by temperature, leading to still another class of sensors. Measurements done on several commercially available fibers indicate adequate sensitivity for selected configurations, but best results will require custom fabricated fibers.