Optical performance monitoring (OPM) is an important approach to determine the quality of optical channels within an optical core network without passing data through optoelectronic regeneration at the monitor points. Using this approach, the quality or"health"of signals can be determined at arbitrary points in a network without knowledge of the transport history of the data or the details of the transmission path. We report experimental results on the use of subcarrier multiplexing (SCM) to perform a variety of monitoring functions including chromatic dispersion monitoring, wavelength registration, power monitoring, and signal-to-noise ratio (SNR) monitoring.
Giammarco Rossi, Timothy E. Dimmick, and Daniel J. Blumenthal, "Optical Performance Monitoring in Reconfigurable WDM Optical Networks Using Subcarrier Multiplexing," J. Lightwave Technol. 18, 1639- (2000)