Optical beating suppressed analog optical transmission using modulated optical pulse train in WDM-SCM access networks

We proposed a new method to suppress the optical beat interference(OBI) in WDM/SCMA network. The proposed scheme uses the modulated optical combs. Since short optical pulse in time domain has broad linewidth in frequency domain, the generated OBI noise by beating of optical comb signals from several optical network unit(ONU)s spreads over wide frequency range. In addition, the chance of optical beating is very low because optical pulse trains from different ONU have different pulse timing. We have demonstrated the proposed idea experimentally. In beating experiment, the carrier-to-noise ratio(CNR) was maintained over 20dBc despite of optical beating. In addition, optical comb modulation scheme showed better performance in BER measurement for 100Mbps BPSK signal compared with the generally used direct modulation case in presence of OBI noise.