A bidirectional common polarization control method for coherent optical FDM transmission system

A bidirectional common polarization control method with a single polarization controller for a coherent optical FDM bidirectional transmission system is discussed. This method is promising for realizing a reliable and low-cost terminal in a coherent multichannel distribution system because the polarization controller can be placed in common only at a central office. Theoretical and experimental results show that the frequency separation delta f has to be 6*bit rate< delta f<120/ Delta tau (GHz) for FSK bidirectional transmission. The method is effective not only for reducing the complexity of the subscriber terminal but also for improving the reliability in a coherent CATV system.<>