Effects of Radiation on Optical Fibers

Abstract

The general mechanism of light transmission loss in optical fiber and the effects of optical fiber under γ-ray radiation environment are introduced. In order to measure the pulse γ-ray radiation-induced loss, an experimental measurement system is developed. Two kinds of pulse γ-ray devices with an average photon energy of 0.3 MeV, a pulse width of 25 ns, a dose rate of 2.03×107 Gy·s-1 and an average photon energy of 1.0 MeV, a pulse width of 25 ns, a dose rate of 5.32×109 Gy·s-1 are employed as irradiation sources in the experiment. The transient radiation-induced loss of pulsed γ-ray effecting on single-mode and multi-mode optical fibers has been measured. Optical fiber transmission systems with several different wavelength lasers such as 405, 660, 850, 1310 and 1550 nm are involved in the experimental measurement system. The results are analyzed subsequently and show that the transient radiation-induced loss will increase as the laser wavelength shifts from near-infrared to visible regions of the optical spectrum. Within dose range of 0.1~3.5 Gy transient multi-mode fiber radiation-induced loss displays a near linear dependence upon the total dose. The conclusion can be deduced that the radiation-induced loss results from two comprehensive effects: It causes additional absorption loss that atomic electron energy levels resonantly absorb propagation photons in the intrinsic material, and changes of refractive index distribution lead to additional waveguide loss also.