High temperature high sensitivity optical fibre sensor based on multimode fibre Bragg grating

A multimode fibre Bragg grating (MMFBG) is experimentally demonstrated in this work. The light from the lead-in optical fibre transmits to the MMFBG, the Bragg gratings in multimode fibres show multiple reflection peaks due to the coupling among all bounded modes. Some reflection peaks are reflected back to the lead-out fibre core by the MMFBG. Finally, the spatial frequency spectra of the reflection peaks are detected by the detection device. As the temperature variates, the changes in the transmission spectrum will be observed. Experimental results show that the MMFBG responds to temperature and the temperature sensitivity is 0.0114 nm/oC. The MMFBG has the advantages of compact structure, anti-electromagnetic interference, and stable chemical property, which has great potential in temperature measurement.