Thermal sensing performance analysis, preparation and application of bimetallic layer MFBG

The FBG(fiber Bragg grating) can be embedded in metal to form smart structure, and to protect the FBG, the surface can be coated with high melting point metal such as Ni. MFBG(metalized FBG) will affect the temperature sensing performance of the FBG. In this paper, the thermal sensing performance of MFBG with single and double metal layers is investigated and the main factors affecting its temperature sensitivity and temperature response are analyzed. The thermal sensitivity of the MFBG gradually stabilizes as the thickness of the metal layer in-creases. The Ni-Ti MFBG (double-layer MFBG with Ni as the outer metal and Ti as the inner metal) was fabricated by magnetron sputtering and electroplating thickening, and a comparative thermal sensing performance experiment was conducted together with the bare FBG. Metallization of the FBG can improve the temperature sensitivity of the FBG. Samples with different metal layer thicknesses were subjected to thermal tests from 0 to 70 degrees C, the obtained data verified the soundness of the presented model. To verify the temperature sensing performance of the prepared Ni-Ti MFBG, it was embedded in a three-phase induction motor and the internal temperature of the motor was monitored. The experiments show that the prepared Ni-Ti MFBG has good tem-perature sensing performance and can accurately sense the motor temperature.