TY - JOUR N2 - A modified optical fibre based Mach-Zehnder interferometer was applied as a sensor to detect wiretapping in long transmission optical fibre lines. The signal consisting of short pulses (around 1 ns) was launched to the input of the interferometer based on the polarization maintaining fibres and polarization elements. When the sensing line was undisturbed, detectors registered only a single pulse. The additional two side pulses appear, if the wiretapping attempt took place. For robust detection of any alarm situation we proposed two-criteria algorithm to minimize false alarm rate. Moreover, slow environmental fluctuations were continuously monitored and compensated by polarization controllers. We measured frequency characteristics of the sensor and performed a hundred wiretapping attempts, which proved high performance of the sensor. L1 - http://journals.pan.pl/Content/115312/PDF/main.pdf L2 - http://journals.pan.pl/Content/115312 PY - 2018 IS - No 2 EP - 187 KW - Optical fibre sensors KW - Mach-Zehnder interferometer KW - Quantum sensors A1 - Życzkowski, M. A1 - Karol, M. PB - Polish Academy of Sciences (under the auspices of the Committee on Electronics and Telecommunication) and Association of Polish Electrical Engineers in cooperation with Military University of Technology VL - vol. 26 DA - 26.05.2018 T1 - Pulsed interferometric optical fibre sensor detecting wiretapping in long transmission lines SP - 183 UR - http://journals.pan.pl/dlibra/publication/edition/115312 T2 - Opto-Electronics Review ER -