Distributed fiber optic acoustic sensor based on sagnac – michelson interferometer

In this study, the data collected from the Sagnac-Michelson interferometer system distributed fiber optic sensor setups used to detect and diagnose illegal entry and exit for places such as borderline, airport, prison, etc. The acoustic effects of four different frequencies were applied in the laboratory environment at three different points on the line, which was formed with a standard fiber communication cable used in communication, twenty km, ten km of reference and ten km of measuring line. While the optical signal circulates on the line, the above-mentioned acoustic effects were applied and the beam reaching the source was demodulated and the acoustic effects were observed by processing the obtained signals. While looking at the first, second and third harmonics, it is analyzed how the harmonics are altered proportionally according to the distance.