<title>Fiber optic intrusion sensor with the configuration of an optical time-domain reflectometer using coherent interference of Rayleigh backscattering</title>

The optical fiber intrusion sensor is investigated in the configuration of an optical time domain reflectometer using coherent interference of Rayleigh backscattering in a single mode fiber. When the modulation pulse width was 4 usec, the spatial resolution of this intrusion sensor was about 400m, the signal to noise ratio was about 3.3 and the bandwidth was about 30.5Hz.