Studies of a system gathering multi-channel visual signals using a single optical fiber and a bidirectional optical amlifier

Bidirectional passive optical network systems including a single trunk fiber and a bidirectional optical amplifier is proposed for the purpose of gathering ITV signals distributed on a line. A FM-SCM technique is used to discriminate the signals. The bidirectional transmission function is realized by using a WDM technique. A novel bidirectional EDFA is applied to long-haul analog signal transmission. The characteristics of gain and noise figure of the EDFA are clarified and they are found to be desirable for the bidirectional analog signal transmission. The transmission properties of the proposed system are confirmed for a 100-km SMF in a cable installed in the field. The satisfied CNR of more than 19dB for the FM modulated video channel can be attained for over the optical line loss of 60dB. Finally, stability of the system is confirmed by a continuous measurement of the SNR for two-weeks.