This paper presents an accurate theoretical model for the study of concatenation of optical multiplexers/demultiplexers (MUXs/DMUXs) in transparent multiwavelength optical networks. The model is based on a semianalytical technique for the evaluation of the error probability of the network topology. The error-probability evaluation takes into account arbitrary pulse shapes, arbitrary optical MUX/DMUX,and electronic low-pass filter transfer functions, and non-Gaussian photocurrent statistics at the output of the direct-detection receiver. To illustrate the model, the cascadability of arrayed waveguide grating (AWG) routers in a transparent network element chain is studied. The performance of the actual network is compared to the performance of a reference network with ideal optical MUXs/DMUXs. The optical power penalty at an error probability of 10-9 is calculated as a function of the number of cascaded AWG routers, the bandwidth of AWG routers, and the laser carrier frequency offset from the channel's nominal frequency.
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