MUTUAL DETERIORATION OF WDM-COUPLED AM CATV AND DIGITAL B-ISDN SERVICES IN SINGLE-FIBER ACCESS NETWORKS

In single-fiber access networks with interactive and distributive services multiplexed at different wavelengths, the interactive signal may disturb the distributive signal and vice versa because of imperfect isolation of the demultiplexing WDM at the subscriber site. In this letter the mutual deterioration of a 622 Mb/s IM B-ISDN signal at 1.3 mum and an AM-SCM TV-distribution signal at 1.55 mum is investigated. Both theory and experiment show that the isolation of the demultiplexing WDM must keep the undesirable 1.3 mum 622 Mb/s IM signal power on the analog receiver below -36 dBm to avoid degradation of the analog system CNR of 47 dB by more than 1 dB. Furthermore, the undesirable 1.55 mum AM-SCM signal power on the digital receiver (either p-i-n of APD) must be kept 10 dB below the sensitivity of this receiver to ensure a power penalty less than 0.5 dB.