High Bit-Rate Receivers, Transmitters, and Electronics

This chapter reviews the design of practical high bitrate receivers, transmitters, and electronic circuits. It illustrates the performance of various detectors, analyzes receiver sensitivity, and considers system impairments. The chapter also explores directly and externally modulated transmitters and modulation formats namely Return-to-Zero (RZ) and Chirped RZ (CRZ). The electronic circuit elements found in the transmitters and receivers— including broadband amplifiers, clock and data recovery circuits, and multiplexers—are also presented. The advent of optical amplifiers particularly, Erbium–Doped Fiber Amplifiers (EDFAs), have revolutionized lightwave systems by making Dense–Wavelength Division Multiplexing (DWDM) the cheapest long-haul transmission technology. Optical preamplifiers using EDFAs exhibit very high receiver sensitivity and are employed extensively in the WDM applications. It is noted that by taking advantage of the high processing speed and large–scale integration of advanced semiconductor IC technologies, many optical fiber transmission impairments at high data rates can be mitigated by low–cost high–performance electronics such as advanced electronic equalizers and spectrally efficient coders and decoders. Thus, high–speed electronics can become a critical enabler to move the capacity of ETDM/WDM optic fiber communication systems to petabits per second with individual channels running at 100 Gbit/s in future.