An optical fiber bend sensor based on a fiber Bragg grating by using a germano-silicate glass optical fiber with depressed-index structure has been developed and its novel bend sensing characteristics was demonstrated. With the increase of bending, the transmission spectrum was linearly blue-shifted without change of optical transmission loss. Total blue-shift of the Bragg reflection wavelength upon bending in the radius of curvature from 20 m-1 to 133 m-1 was − 0.13 nm.
Possibility of a Co/Fe co-doped alumino-silicate optical fiber as a radiation dosimeter application was investigated from the measurement of radiation-induced optical attenuation (RIA). The RIA at 1310 nm of the optical fiber upon gammaray irradiation was found to increase linearly with the radiation dose. The extent of the RIA increase to 11,900 dB/km at radiation dose rate of 20 Gy/min for 1 hour was 70 times larger than that of the reference single mode fiber and the RIA remained almost constant after 5 minutes of the irradiation termination.