OFDM subcarrier monitoring using high resolution optical spectrum analysis

In this paper, we demonstrate in-band OSNR monitoring of individual subcarriers in optical OFDM using a high-resolution optical spectrum analyzer. The relationships between OSNR, electrical SNR and BER at the receiver are experimentally analyzed and compared to theoretical results. A linear dependency in dB is found between electrical SNR and subcarrier OSNR for total OSNR values below 26 dB. Above this limit, the correlation degree decreases due to the electrical SNR degradation at the edge subcarriers. The BER analysis per subcarrier also shows a clear correlation with the proposed in-band optical measurements.