Low-Cost PMD-Insensitive and Dispersion Tolerant In-Band OSNR Monitor Based on Uncorrelated Beat Noise Measurement

A polarization-mode-dispersion-insensitive and dispersion tolerant in-band optical signal-to-noise-ratio monitor based on uncorrelated beat noise measurement is proposed and demonstrated. The proposed technique uses an optical delay line interferometer in recovering symmetrical signal samples and exploits the benefits of low-speed balanced receivers and digital signal processing in measuring the uncorrelated beat noise.