In order to adapt to the ever-increasing demands for high-speed transmission and distance-independent connectivity, today's network operators are implementing 100 Gb/s per dense wavelength division multiplexing (DWDM) channel. At those data rates, the performance of fiber-optic communication systems is degraded significantly due to intra-and inter-channel fiber nonlinearities, polarization-mode dispersion (PMD), and chromatic dispersion. In order to deal with these channel impairments, novel advanced techniques in modulation, detection, coding and signal processing are needed.This groundbreaking book represents a coherent and comprehensive introduction to the fundamentals of optical communications, digital signal processing (DSP), and coding for optical channels. This book:Is the first to integrate the fundamentals of coding theory and DSP with the fundamental of optical communication;Provides detailed coverage of joint coding and modulation for optical communications;Presents turbo equalization for joint iterative channel equalization and soft decoding on optical channels;Provides in-depth coverage of codes on graphs, including LDPC and turbo codes, and describes their application to optical channels;Includes coverage of both fiber-optics and free-space optical (FSO) channels;Is the first to cover the channel capacity of fiber-optic communication systems;Is the first to describe constrained coding for optical channels.