We present here a novel method for failure detection of composite materials CFRP based on measurement of amplitude of vibrations of subjected structure using fiber optic sensing coil. We used PZT actuators, bonded in different configurations over the surface of the composite plate, to generate elastic waves. They make a unique acoustic response that depends on the type and health of the structure. The sensing configuration is "all-in-fiber" Michelson interferometer based on 3x3 single mode fiber optic directional coupler, used for quadrature signals generation. The interferometric 2n ambiguity is overcome using a low coherence super luminescent diode at 1310 nm as the light source. The sensing coil is glued to the composite material while reference coil is not in direct contact with the material. The amplitude and shape of the signal depends on the strain that elastic waves produces by traveling through the structure and fiberoptic coil applied over it.