Optical Performance Monitoring
Optical performance monitoring of signal quality is one of the key enablers of intelligent optical networks and software defined optical transmission, suitably interoperating the physical infrastructure with the network control
layer. Precisely, monitoring of the transmission impairments is needed at several points of the network, where several functionalities are performed. Reconfigurable optical add-drop multiplexers and optical cross- connects are usually configured and managed by a control plane which requires also in-band knowledge of the transmission impairments. This monitoring information is used by this control layer for properly managing the network resources. Numerous techniques have been proposed for monitoring relevant optical parameters, including OSNR and dispersion.
The techniques analyzed by the ONS department include direct optical spectrum analysis and OFDM self-monitoring. Interestingly, advanced parameters can be monitored at the subcarrier level in systems with subwavelength granularities (e.g. O-OFDM).