To perform distributed sensing with an optical fiber using Brillouin
scattering, a light pulse is transmitted into the optical fiber, where
the transmitted light pulse has a first frequency. Backscattered light
and optical local oscillator light are combined, where the backscattered
light is received from the optical fiber in response to the transmitted
light pulse, and where the optical local oscillator light has a second
frequency. A frequency offset is caused to be present between the first
frequency of the transmitted light pulse and the second frequency of the
optical local oscillator light, where the frequency offset is at least 1
GHz less than a Brillouin frequency shift of the backscattered light.
Spectra representing Stokes and anti-Stokes components of the
backscattered light are acquired, where the Stokes and anti-Stokes
components are separated by a frequency span that is based on the
frequency offset.