Gamma radiation tests of radiation-hardened Fiber Bragg Grating based sensors for radiation environments

In the framework of a KIC InnoEnergy funded project radiation-hardened Fiber Bragg Gratings (FBG) are developed to withstand high levels of radiation dose at high temperatures for their implementation in temperature- and strain sensors for nuclear facilities, accelerators or space. This paper presents gamma radiation test results obtained at room and elevated temperature in hardened FBGs as well as in the optical fibers used for their production. It is shown that radiation-induced Bragg wavelength shift (BWS) is below ±2 pm corresponding to ±0.2°C and does not influence the sensor performance even after a total dose of 200 kGy(SiO2) and operating temperature up to 350°C.