Experimental study of optical fibers for the application of fiber radiation sensor

We have measured radiation (gamma ray) induced loss of P-doped and Ge-doped fibers with different dopant concentrations and core diameters for different dose rates. The following conclusions can be obtained from our experiment: 1. The fibers we tested (P and Ge doped) have no evident recovery after gamma ray radiation. 2. No evident photo-bleaching effect had been observed by irradiating the fiber with diode laser of wavelength 630 mu m 3. Optical fiber with higher dopant concentration does not mean more sensitive. 4. For fiber length as short as 0.3 m, the sensitivity of P-doped fiber (0.6-0.8 dB/m for total dose of 4 Gy) is sufficient for the measurement of dose range for patients.