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.