OSNR monitoring technique based on orthogonal delayed-homodyne method

The authors propose and demonstrate a simple technique to monitor the optical signal-to-noise ratio (OSNR) of wavelength-division-multiplexing (WDM) signals using the orthogonal delayed-homodyne method. This technique estimates the OSNR by analyzing the receiver noise characteristics after eliminating the signal components at a specific frequency within the modulation bandwidth. The results show that the OSNR of WDM signals could be monitored with accuracy better than 0.5 dB in the range of 12/spl sim/35 dB.