Fiber optic temperature sensor using a Y2O2S:Eu thermographic phosphor

摘要

Abstract: This report details the development and testing of a thermographic-phosphor-based fiber-optic temperature sensor. The sensor is constructed by removing a region of the fiber jacket and cladding, then coating the exposed core with yttrium oxysulfide doped with a europium activator (Y$-2$/O$- 2$/S:Eu). When photoexcited, the europium in the host lattice emits a sharp-line fluorescence spectrum that is characteristic of the temperature of the host crystal lattice. By measuring fluorescence lifetimes, we can deduce the temperature of an optical fiber that is in thermal contact with the fiber. Two different distributions of Y$-2$/O$-2$/S:Eu in the cladding region were evaluated with regard to light coupling efficiency. Theoretical waveguide calculations indicate that a thin core/cladding boundary distribution of Y$-2$/O$-2$/S:Eu couples light more efficiently into the cores guided modes than does a bulk distribution of phosphor in the cladding. The sensor tests showed reproducible response from 20 to 180 degrees Celsius. This technique has several advantages over other fiber optic temperature sensing techniques. !16