Security monitoring for optical network

Abstract

Apparatus () for an optical communications network has optical paths for optical traffic, and optical ports (), one of which is an unused input port (). A security monitoring system () has a blocking part () comprising an interface () coupled removably to the unused input port () to occupy it to prevent unauthorized access. A light source is optically coupled to the interface () such that, when the interface is coupled to the unused input port, light can be transmitted through the interface () into the unused input port (). An optical detector () can detect light reflected back from the interface (), and there is alarm circuitry () configured to output an alarm signal based on the detecting of the reflected light. This monitoring can help make the node more secure from interference such as the introduction of a noise signal. The system can be passive or active, and does not require a change in the installed node configuration and so can be added easily to existing infrastructure.