Crosstalk in direct-detection optical fiber FDMA networks

Abstract

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. 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. 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.