Reflection-Type LPFG Temperature Sensor Based on CFBG Fabricated by Femtosecond Laser

This is the authors' abstract. We don't add key points for this paper.

In this paper, a chirped fiber Bragg grating (CFBG) is cascaded with a long-period fiber grating (LPFG) to form a probebased temperature sensor. The acquisition of LPFG resonance peak signals by CFBG in specific bands enables probe-based monitoring. The femtosecond laser point-by-point inscribing technique is utilized in the preparation process of both gratings, giving rise to a sensor featuring excellent temperature resistance. Numerical simulations and experimental tests have shown good agreement in verifying the transmission characteristics of the sensor within the temperature range of 30 to 200 °C. The results indicate that the sensor has a temperature sensitivity of 70.19 pm/°C (LP05, 30 to 200 °C). By adjusting the CFBG bandwidth, the sensor can monitor LPFG transmission spectra in different temperature range and the temperature sensitivity of the sensor is adjusted by the resonant modes of LPFG. The sensor achieves probe-based temperature monitoring without the need for additional technical means, promising widespread application in the field of temperature sensing.