Behavior of Bragg gratings, written in germanosilicate fibers, against /spl gamma/-ray exposure at low dose rate

Bragg gratings have been written within four germanosilicate fibers either by a pulsed or by a continuous-wave exposure of each fiber to a coherent UV two-beam interference pattern. These gratings have been exposed under steady state conditions to /spl gamma/-ray doses as high as 10
⁴
Grays. The dose rates ranged between 10 Gy/h and 1.3×10
²
Gy/h. The transmission spectra of the fibers have been recorded during and after the /sup 60/Co irradiation, near the grating Bragg wavelengths. Whereas the induced loss reached 600 dB/km near 1.3 μm, no significant change in the spectral characteristics of the gratings could be detected within the experimental accuracy, enabling their future use in a nuclear environment.