Crosstalk in Direct-Detection Optical Fiber FDMA Networks

Direct-detection DD optical fiber frequency division multiple access FDMA is a simple and practical alternative to optical heterodyne FDMA. Previous works on estimating the performance of DD optical FDMA networks have usually focused only on the linear crosstalk degradation, typically relying on simplifying approximations such as the dominance of the adjacent channel interference 1, 4. Other sources of performance degradation such as signal loss due to optical predetection and electrical postdetection filtering, intersymbol interference ISI due to the optical filtering, and channel beats or nonlinear crosstalk are usually ignored. This paper presents a more precise analysis that takes into account the effect of optical and electrical filtering, ISI, and linear crosstalk 3. The model used here is valid for arbitrary optical filter transfer functions and received pulse shapes. We consider in this paper only On-Off-Keyed OOK modulation extending the analysis to Frequency- Shift-Keyed FSK modulation is straightforward, but is not discussed here.