A method that utilizes a dispersion-shifted fiber having compound
compositions with different temperature coefficients in core to
simultaneously measure the distributed strain and temperature based on
Brillouin frequency shift is disclosed. The present method includes the
steps of obtaining mean two peak frequencies in a multi-peak Brillouin
spectrum of the dispersion-shifted fiber, determining a temperature change
according to the formula of a Brillouin frequency shift of the peak
relating to strain and temperature conditions of the fiber, and
determining a strain change through the formula. In a 3682-m sensing
length of Large-Effective-Area NZ-DS fiber, a temperature resolution of
5.degree. C., a strain resolution of 60 .mu..epsilon. and a spatial
resolution of 2 m are achieve simultaneously.
