High time resolution fibre optic sensing system based on correlation and differential technique

A novel fibre optic sensing system with a high time resolution of less than 0.04 ps based on an optical pulse correlation measurement mechanism and differential detection technique is investigated. The optical pulse correlation state corresponding to time drift in fibre optic transmission lines is detected by SHG. The results of temperature and strain sensing experiments demonstrate an excellent linear relationship between the differential signal and the measurands inducing time drift of the optical pulse through a fibre optic. Based on the sensing system, a temperature resolution of 0.04 m ◦C and a strain resolution of 0.2 με are obtained, respectively, which indicate that the sensing system can be successfully applied to monitor the environment conditions around fibre optic transmission lines with high resolution.