All-Optical Monitoring of Noise Spectral Density

We propose an all-optical performance monitor of in-band impairments statistics. The method is implemented in the optical frequency domain, i.e., employing the optical PSD as the explanatory observable. The technique offers various beneficial traits. It operates with multi-impairments, i.e., monitors every network impairment simultaneously, e.g., when in the presence of strong NLI can correctly account for its contribution. It is cost-effective and shown to have a fast response time. It is rate and modulation independent. Although we report a single channel validation as a proof-of-concept, we see no obstacle to operate in a multi-channel context. We see two main advantages of this method. First, the possibility to be employed everywhere since OSA can be distributed ubiquitously along the optical path, allowing per-span and per-wavelength monitoring and optimization. Second, the capability of determining pure-optical impairments, helping the design of open submarine cables.