Raman Crosstalk Suppression in CATV Overlay Passive Optical Network

In cable television (CATV) overlay passive optical networks (PONs), where a CATV signal copropagates with a downstream baseband signal, the crosstalk components mediated by stimulated Raman scattering (SRS) limit the performance of low-number CATV channels. In this letter, we propose and demonstrate a way of reducing the SRS-induced crosstalk in CATV overlay PONs. The proposed scheme utilizes a high-speed polarization scrambler in the transmitter to make the SRS-induced crosstalk independent of polarization evolution along the fiber and a subtractor module to compensate for the crosstalk. Our demonstration shows that crosstalk can be reduced by 9 dB