Optical low coherence reflectometry for measuring a stationary Brillouin grating induced under uniform pumping in a short optical fiber

We demonstrate that valuable information on the distributed Brillouin spectra of an optical waveguide can be derived from a stationary Brillouin grating measurement under uniform pumping with optical low coherence reflectometry. We up-convert the frequencies of the probe and pump light waves by the Brillouin frequency and detect the Stokes light in the same way that we detect the Fresnel and Rayleigh backreflections in the fiber. The pump light wave that propagates toward the optical balanced mixer is blocked by using a polarization diversity technique and the distributed Brillouin gratings excited in an 82-cm long non-birefringent single mode fiber are measured at a spatial resolution of the order of 1 mm.