Difference frequency stimulated Brillouin scattering water temperature measuring method

The invention discloses a difference frequency stimulated Brillouin scattering water temperature measuring method. According to the method, a single-frequency pulsed laser emits P polarization-state pulsed laser, and the P polarization-state pulsed laser is divided into a detection laser beam and a reference laser beam through a first polarization beam splitter; S direction polarized light corresponding to the reference laser beam and the detection laser beam enable the backward stimulated Brillouin scattering light signal generated by tested seawater to correspond to the S direction polarizedlight, after the two beams are combined through a 50% beam combiner, interference is carried out on the photosensitive surfaces of two high-speed detectors, respectively, so as to generate differencefrequency light signals, the high-speed detectors convert the difference frequency light signals into difference frequency electric signals, the difference frequency electric signals are amplified through two wideband amplifi