Patent ID: 8280253

Claim:
An optical telecommunications network terminal including: a generator device for generating downlink optical signals; and an optical signal receiver device for receiving uplink optical signals; the optical signals being conveyed in optical transmission means connected to the terminal, wherein the generator device includes means for generating a continuous downlink optical signal in the optical transmission means at wavelength λii and having an initial power greater than a power threshold for the occurrence of a stimulated Brillouin effect, above which threshold said continuous optical signal induces a continuous Brillouin backscattering uplink optical signal in the optical transmission means at wavelength λ′ii, and the optical signal receiver device includes means for analyzing the power of said continuous Brillouin backscattering optical signal at wavelength λ′ii, and the optical transmission means include an optical fiber and the analyzer means include means for measuring the power of the Brillouin backscattering signal and means for determining an optical fiber length as a function of the measured signal power.