AN INTRUSION DETECTION SYSTEM FOR USE ON SINGLE MODE OPTICALFIBER USING A POLARIMETER

摘要

A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transm it end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until a n intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitt er and less than all four of the Stokes parameters. It can use a polarimeter ty pe function limited to linear and circular polarization or two linear polarizer s at 90 degrees