Abstract: An optical fiber strain-temperature sensing system includes first and second optical sources respectively generating first and second light signals having different wavelengths. Optical circulators direct the light signals to an external sensing cable for the respective generation of first and second Brillouin scattered light signals. First and second frequency mixers have a first input respectively coupled to the first and second optical light sources. The optical circulators direct the first and second Brillouin scattered light signals respectively to second inputs of the first and second frequency mixers. First and second transducers are respectively coupled to an output of the first and second frequency mixers and are respectively configured for generating first and second electrical signals indicative of a Brillouin frequency shift of the first and second light signals.