Intrusion detection system for a multimode optical fiber using a bulk optical wavelength division multiplexer for maintaining modal power distribution
US7403674B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 2006 |
| Grant date | Jul 22, 2008 |
| Priority date | — |
| Expiry date | Aug 2, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/85
- WIPO fieldOptics
- WIPO sectorInstruments
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. A fiber being used for data transmission can be monitored for intrusion by introducing a monitor wavelength different from that of the data signal. Central to this invention is the use of a bulk optic (commonly referred to as a pass/reflect) wavelength division multiplexer, one which maintains the modal distribution within the fiber.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.