Theoretical and experimental investigation on temperature coefficient of optical fiber delay at cryogenic ranges

Abstract The temperature coefficient of optical fiber delay is theoretically and experimentally investigated under the condition of cryogenic temperature. The effects of temperature variation on the refractive index of the fiber core and the strain of the fiber coating are studied in the theoretical analysis. Based on the analysis, an equation that linearly relates the optical fiber delay and the temperature, which induces the changes of the fiber-core refractive index and physical length, is derived. It is found that the temperature coefficient of optical fiber delay is constant at the cryogenic temperature condition. In the experiment, the temperature coefficient of optical fiber delay is measured to be a constant of 50.9ps•km−‍1•K−1 at the temperature range from 110K to 220K. Good agreement is found between the theoretical analysis and the experimental verification.