Automatic on-line monitoring and optimization of optical network

Abstract

An on-line technique which allows the monitoring and adjustment of switching node control parameters within an optical network. More specifically, a technique wherein a low-frequency modulation is induced upon an optical signal as it passes through a node within a switch or sub-system by varying the control voltage applied to that node about what is assumed to be the optimum control voltage level, the optical signal at position downstream from the node is analyzed to ascertain the amplitude, frequency, and phase characteristics of the induced low-frequency modulation, and a determination is made, on the basis of the amplitude, frequency, and phase information, as to the whether the control voltage which was assumed to be optimal is indeed at the correct level to insure proper operation of the node. The amplitude of the induced low-frequency modulation may be maintained at low level so as not to interfere with the transmission of the primary information and data carried by the optical signal. Analysis of the amplitude, frequency, and phase of the modulated signal may be performed at a single fixed location within the network. Furthermore, multiple switching nodes may be monitored simultaneously from a single location within the network by modulating each node at a unique frequency. This allows each modulated signal received to be differentiated from all others, and readily identified as having originated at a particular node.