Regularized Sparse Recovery for Optical Power Monitoring With Low-Cost Tunable Optical Filters

We propose a regularized sparse recovery (RSR) technique to monitor optical power from the broadened optical spectrum acquired by scanning a tunable optical filter (TOF). The key idea of RSR is to find a smooth but sparse signal spectrum that matches the observed data of a broadened spectrum model within a tolerable error. Experiments demonstrated that RSR can be used to monitor accurately the power of mixed 10-G/40-G wavelength-division-multiplexing channels with 50-GHz channel spacing using commercial TOFs. This technique also has higher immunity to measurement and TOF response errors than the regularized least square method. It does not require strong repeatability of TOF response and makes the low-cost TOF suitable for optical power monitoring.