Förfarande och apparat för att överföra information via en optisk fiber, varvid störning detekteras och/eller lokaliseras

摘要

In conventional manner, an information-carrying main wave and an auxiliary wave are injected into a link fiber. The auxiliary wave is chosen to couple are easily with the outside than the main wave. According to the invention, test modulation is applied to the auxiliary wave and the phase of the wave backscattered by the fiber is measured. The invention is applicable to transmitting confidential information.