Theoretical and experimental investigations on the temperature dependence of the refractive index of amorphous silica

•A rigorous theoretical model for the temperature dependence of the refractive index of amorphous SiO2 is presented.•Delay time testing technique is used to investigate the temperature dependence of the refractive index of amorphous SiO2.•The refractive index of amorphous SiO2 is shown to be proportional to the temperature in the range of 301-1275 K.

Though people have experimentally studied the temperature dependence of the refractive index (RI) of optical fibers made of amorphous silica (a-SiO2), the temperature ranges in the previous experiments are usually below 800 K, and a rigorous theoretical model for the experimental results has still been absent. In this paper, the temperature dependence of the RI of a-SiO2 is studied theoretically and experimentally, where by means of an optical fiber delay line, the experiment is carried out in the temperature range of 301–1275 K for the first time, and the theoretical result agrees well with the experimental one. Our work has potential application in temperature sensors by means of optical fiber delay lines.