Abstract: The formation of a mechanical wave having a greater amplitude and therefore a stimulated Brillouin scattering is prevented in that the light waveguide transmission is divided into different sections and in that the sections are acoustically decoupled from one another. This can also be achieved in that the phase relationship between the fed-in and optical wave or, respectively, backscattered light wave is disturbed by longitudinal non-homogeneities of the fiber or by purposeful destructive interference.

Abstract: A low-noise bidirectional optical amplifier is arranged so that the bidirectional transmission fiber is divided into two unidirectional branches by two circulators. Each of the branches is equipped with at least two amplifiers with at least one optical filter element disposed therebetween. Preferably, the first amplifier of each unidirectional branch is an active fiber which is pumped through a wavelength-division multiplex coupler that is arranged to follow the active fiber.