Detection of anomalous events in optical networks

A computer system comprising:

• a digital processor;
• a network interface configured to be in communication with a plurality of nodes of an optical network to collect information about quality of transmission (QoT) on a plurality of wavelength channels received at one or more nodes of the optical network;
• a memory device coupled to the digital processor and comprising instructions which, when executed by the digital processor, cause the digital processor to detect coincident drops in QoT on the plurality of wavelength channels, to determine a QoT drop function based on the detected coincident drops in QoT, the QoT drop function indicating for each of at least some of the plurality of wavelength channels a change in a QoT metric corresponding to a respective drop in QoT among the detected coincident drops in QoT, and to detect a signature of a network event in the QoT drop function.