High-resolution measurement of stimulated Brillouin scattering spectra in single-mode fibres

A new technique is introduced for stimulated Brillouin scattering spectral characterisation. It provides accurate measurements of the amplitude and ph ase of the Brillouin gain and loss spectra with high frequency resolution a nd stability. Furthermore, only narrow-electrical-bandwidth electro-optical components and instruments are needed in its experimental implementation. The measurement principle is based on translating the Brillouin spectral in formation from the optical to the electrical domain. This leads to frequenc y resolutions of the measurements in the kilohertz range because the Brillo uin spectra are scanned by sweeping an electrical rather than optical carri er, The experimental setup relies on a Brillouin-erbium fibre laser to gene rate the optical signals needed to perform measurements, so that problems r elated to optical frequency drift are avoided. Measurements of Brillouin ga in and loss spectra in a 25 km reel of standard single-mode fibre are prese nted demonstrating the capabilities of the technique.