Patent · US Expired

Optical fibre with increased security

US4134642A · kind A · utility

49Cited by
4References
14Claims
0Family size

Assignee

Inventors

Key dates

Filing dateMay 2, 1977
Grant dateJan 16, 1979
Priority date—
Expiry dateMay 2, 1997

Classification

  • Technology area (CPC G)Physics
  • CPC primaryG02B6/0281
  • WIPO fieldOptics
  • WIPO sectorInstruments

Abstract

An optical fibre has a plurality of light conducting cores surrounded by a cladding layer of lower refractive index than the cores. A light conducting layer is on the cladding layer with a refractive index higher than that of the cladding layer, and a second cladding layer surrounds the light conducting layer and has a refractive index lower than that of the light conducting layer. Data signals can be propagated in the cores and a monitoring signal in the light conducting layer. Any attempt to tap the fibre to abstract data information results in aberration of the monitoring signal. Thus there is provided a secure optical fibre cable.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.