Coupled-fiber Bragg grating sensor structure for cryogenic conditions

摘要

We propose a fiber-optic sensor structure for simultaneous strain and temperature monitoring in cryogenic conditions. The polymer coated fiber Bragg grating sensor makes it a suitable candidate for cryogenic temperature measurement. FBG have been shown to have an enhanced sensitivity of 48 pm ℃~(-1) from -185 to 25 ℃. The cross-sensitivity problem has been solved by introducing a glass capillary tube to encapsulate the coated FBG. The thermal expansion of capillary material was compensated by cleaving the one end of FBG free and the other end with the temperature resistant epoxy resins. Experiments results validate the proposed method can successfully monitor the strain and temperatures at cryogenic temperatures.