Highly-Sensitive and -Linear Cryogenic Temperature Response of Long-Period Fiber Gratings Written on B–Ge-Codoped Photosensitive Fiber

In this paper, we report the highly-sensitive and -linear cryogenic temperature response of long-period fiber gratings (LPFGs) written on B–Ge-codoped photosensitive single-mode fiber. The resonance wavelength of the fabricated LPFG was monitored at a temperature range from 77 to 295 K. The temperature sensitivity of the resonance wavelength was measured as ∼398 pm/K, which was higher than that of fiber grating sensors in a comparable cryogenic temperature range reported by other research groups. In particular, the linearity of the temperature response curve was very good (R 2 value of ∼0.9979).