Optical transmission system design

Abstract This chapter introduces basic rules and major considerations in the design of a fiber-optic communication system based on binary intensity-modulation and direct-detection (IMDD). While bit error rate (BER) is the ultimate performance measure of the transmission quality, Q-value is a convenient parameter which is directly related to the BER. System performance degradation is attributed to the combination of waveform distortion and random noise, and they can be separately evaluated to simplify system design and performance evaluation. Instead of using receiver sensitivity as the system performance criterion, required optical signal-to-noise ratio (R-OSNR) is the most relevant parameter to specify optical systems employing optical amplifiers. Various sources of system performance degradation are discussed in this chapter, and a semi-analytical approach to evaluate nonlinear crosstalks in fiber-optic systems is presented, which include cross-phase modulation, four-wave mixing, and modulation instability.