System-level radiation hardening of fiber-optic sensor for applications in the radiant condition

Abstract In order to improve the radiation hardness of fiber-optic sensor for applications in the radiant condition, especially in the condition that the commercial optical components are used, the system-level radiation hardening technique is proposed by taking into account fiber-optic Sagnac interferometer as an example, in this paper. A model for describing the relationship between the random walk coefficient (RWC) of the closed-loop Sagnac interferometer and the optical parameters in optical loop, the radiation-induced attenuation (RIA) in fiber coil is presented. Then, the numerical simulation for the influence of optical parameters on the degradation sensitivity of RWC to the increase of RIA in fiber is implemented. It is found that the tolerance of fiber-optic Sagnac interferometer on the RIA in fiber coil can be improved by using the light source with high output power, making the diameter of fiber coil as large as possible, and utilizing the over-modulation technique. Furthermore, increasing the output power of light source is the most efficient and feasible method. The increase of output power from 0.2 mW to 3 mW can reduce the degradation of RWC by more than one order of magnitude.