Performance evaluation of ASK multichannel coherent optical systems

In this work we evaluate the impairments due to laser phase noise in multichannel coherent optical systems using a heterodyne ASK modulation scheme. The effects of crosstalk due to a finite value of the channel spacing are considered in a system employing a frequency division multiplexing technique. The phase noise and the frequency spacing between adjacent channels are the fundamental parameters which determine the design criteria (e.g. the bandwidth of the intermediate frequency filters) and the performance of the receiver. The accurate statistical characterization of the filtered phase noise and of the crosstalk is the key to get accurate results: to this aim the exact moments of the random processes related to the phase noise and to the crosstalk interference are used together with a Gaussian Quadrature Rule for the evaluation of the error probability.