Distributed fibre analysis with cm resolution using gated flexural acoustic waves

For years, the in fibre acousto-optic interaction has been developed assuming harmonic excitation of a propagating acoustic mode - either the fundamental flexural, longitudinal or torsional mode-, and exploiting the dynamical properties of the interaction by controlling the amplitude and frequency of the RF voltage used for the generation of the acoustic wave. More recently, some works have investigated the new possibilities that are enabled by using standing and pulsed acoustic waves. However, the study of the in-fibre acousto-optic interaction with a time-domain distributed approach has been hardly exploited. Here, some experimental results in which the acousto-optic interaction is excited with short acoustic wave packets, while the optical transmittance is recorded in an oscilloscope as a function of time, are presented. This allows analyzation of the distributed effects along the fibre, enabling a truly time-domain distributed analysis of the in-fibre acousto-optic interaction.