Intrusion detection system for use on single mode optical fiber using a storage register for data

Abstract

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 transmit 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 an 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 splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

Description

RELATED APPLICATIONS [0001] This application claims priority under 35 U.S.C. 119 from Provisional Applications 60 / 643,001, 60 / 643,002, 60 / 643,003 and 60 / 643,004 all filed Jan. 12, 2005. [0002] Reference is made to co-pending applications filed on the same date as this application by the same inventors, the disclosures of which are incorporated herein by reference as follows: [0003] Application Serial No. (not yet known) attorney docket number 85570-302 entitled AN INTRUSION DETECTION SYSTEM FOR USE ON SINGLE MODE OPTICAL FIBER USING FRESNEL REFLECTIONS. [0004] Application Serial No. (not yet known) attorney docket number 85570-202 entitled AN INTRUSION DETECTION SYSTEM FOR USE ON SINGLE MODE OPTICAL FIBER USING A POLARIMETER. [0005] Application Serial No. (not yet known) attorney docket number 85570-232 entitled AN INTRUSION DETECTION SYSTEM FOR USE ON SINGLE MODE OPTICAL FIBER USING A SIMPLIFIED POLARIMETER. [0006] Application Serial No. (not yet known) attorney docket number 85570...

AI Technical Summary

Benefits of technology

"The present invention provides an improved method for detecting movement of an optical fiber by using a scattering signal to monitor changes in polarization. This method can detect changes in polarization before any optical power loss occurs, making it possible to detect intrusion activity before it becomes a security threat. The method involves injecting polarized light into the fiber and detecting the movement of the light signals along the fiber using a series of received light signals. The received light signals are analyzed to determine the changes in polarization caused by the movement of the fiber. The changes in polarization are detected by comparing the received light signals to previous signals and monitoring the changes in polarization over time. The invention can be used in telecommunications systems to detect and locate movement of the fiber caused by intrusion or other factors."

Problems solved by technology

However, this adds to the complexity of the network and burdens processing power.

Current IDSs are hampered by Base-Rate Fallacy limitation, which is the inability to suppress false alarms.

Additionally, software-based IDSs do not provide protection against passive optical fiber tapping, which can go undetected by the network hardware.

This causes a small spatial distortion in the core / cladding guiding properties and a fraction of the light escapes the fiber.

This results in a loss of received optical power of only 0.04 or 0.004 dB and is impossible to detect reliably by power measurement methods.

Images