Numerical and Experimental Investigation of a Fiber-Optic Sensor Consisting of a Fiber Bragg Grating in a Two-Mode Fiber for Simultaneous Sensing of Temperature and Strain

摘要

We investigate a fiber-optic sensor for the simultaneous measurement of temperature and strain. Itrnconsists of a fiber Bragg grating (FBG) inscribed into a short piece of two-mode fiber (TMF) that isrnspliced in-between a standard single mode fiber (SMF). By monitoring the spectral shift of the Braggrnwavelength and the mode interference (MI) pattern, both physical quantities can be determinedrnsimultaneously. The sensor response to temperature and strain was investigated theoretically using arnnumerical sensor model and the results were verified experimentally. The measured temperature andrnstrain sensitivities of the MI are found to be 175,3 pm/K and 3,24 pm/με, which is large compared tornthe FBG having sensitivities of 9,6 pm/K and 1,04 pm/με. The simultaneous measurement ofrntemperature and strain was tested experimentally yielding promising results with maximum errors ofrnmeasurement of 1,5 K and 82 με respectively.