Third-order intermodulation distortion in coherent subcarrier-multiplexed systems

Distortion due to third-order intermodulation products in coherent optical subcarrier-multiplexed communication systems is investigated. It is shown that intermodulation distortion limits both the number of data channels and the maximum obtainable carrier-to-noise ratio. Analysis is restricted to systems operating over one octave. Experimental results on the optimal phase modulation (PM) index based on the number and frequency allocation of the microwave channels are discussed. The conditions for optimal performance with respect to channel number and phase modulation index are given.<>