Method and apparatus for securing information communicated through optical fibers

摘要

This invention relates to a technique for protecting information from intrusion that is transmitted through optical fiber. The new method relates to transmitting energy at multiple wavelengths along a single mode optical fiber. The wavelengths can be propagated in single mode or alternatively n single mode or in high order modes. Energy at one or more wavelengths constitutes guard channels which have an enhanced power loss effect by selection of an appropriate cut-off wavelength of the single mode optical fiber. These guard channels can be monitored for power loss to detect intrusion. An apparatus is also described.