Remote location of active section of fiber in a multimode intrusion detection system
US7376293B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 2006 |
| Grant date | May 20, 2008 |
| Priority date | — |
| Expiry date | Oct 2, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/421
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Intrusion detection of one section only of a multimode fiber uses a light signal launched into the fiber at a location spaced from the source through a single mode fiber to establish a narrow spectral width, under-filled non-uniform mode field power distribution in the fiber. A small portion of the higher order signal modes at the a second location also spaced from the destination is sampled by a tap coupler and monitored for transient changes in the mode field power distribution which are characteristic of intrusion to activate an alarm. The active signal of a multimode optical fiber is monitored for both signal degradation and transient power disturbance patterns that could indicate fiber damage or physical intrusion. A translator can be provided in an existing optical fiber system in which the data signals are translated in wavelength and/or launch conditions to optimize the monitoring signals in an otherwise non-optimized system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.