Effect of amplifier spacing on four-wave mixing in multichannel coherent communications

Abstract

The buildup of four-wave mixing (FWM) is studied for the case of a multichannel coherent system using cascaded optical fibre amplifiers. It is shown, both analytically and numerically, that FW interactions can be either reduced or resonantly enhanced depending on the choice of the amplifier spacing. An example is given of a three channel phase modulated system with a channel separation of 12.5 GHz transmitted over 1000km. For this example, resonance of FWM occurred at an amplifier spacing of 53 km.