Fig. 1. Multi-longitudinal mode fiber laser sensor temperature measurement system. (a) Temperature measurement system; (b) automatic data acquisition process

Fig. 2. Beat frequency signals collected at different time

Fig. 3. Finding the position of the center point of the rectangular frame

Fig. 4. Position change of the center point of the beat signal

Fig. 5. Position change of the center point of the beat frequency signal at different temperatures

Fig. 6. Variation curve of the center point position of beat frequency signal with temperature

Fig. 7. Temperature response of beat frequency signal