A Template-Matching Method for Optical Power Monitoring

In this letter, we propose a template-matching (TM) method for monitoring optical power from greatly broadened optical spectrum acquired by a scanning tunable optical filter (TOF). Conventional methods, such as least squares (LS) and regularized spare recovery (RSR) methods, suffer performance degradation when the power discrepancies between adjacent channels are significant. In addition to the exploitation of prior information on channels and signal modulation formats, the proposed TM method further uses L₁ optimization to alleviate the relative error in power estimation, especially for channels with weak signal power. Experimental results demonstrated that the TM method can be used to accurately monitor signal power of mixed 10/40-Gb/s wavelength-division-multiplexing (WDM) channels with 50-GHz channel spacing via commercial low-cost TOFs. This technique also has higher immunity to system errors as well as the dynamic range of the signal power discrepancies between adjacent channels.